# Discussion of laminar vs turbulant flow



## Phil Edwards (Jan 22, 2004)

Hey y'all,

Niko and I had a really stimulating talk the other day about flow regimes in planted aquaria and it got me thinking. His example of laminar flow in the San Marcos in a previous post is awesome and I thought I'd expand on it a little. After keeping planted tanks by rote for so long, having a deeper understanding of the science behind what's going on in my aquaria has helped me immesurably. I thought I'd talk a little bit about what I've learned in the hopes it'll increase your understanding of your aquaria and improve your hobby just as it has mine.

Reynold's number (Re) http://en.wikipedia.org/wiki/Reynolds_number

The initial statement "...such as laminar or turbulent flow: laminar flow occurs at low Reynolds numbers, where viscous forces are dominant, and is characterized by smooth, constant fluid motion, while turbulent flow occurs at high Reynolds numbers and is dominated by inertial forces, which tend to produce chaotic eddies, vortices and other flow instabilities." contains the critical element' smooth, constand fluid motion vs. chaotic and other flow instabilities.

Going back to the San Marcos and other plant-filled streams many of us have seen; the flow in such streams is for the most part laminar. It may not be purely unidirectional and constant throughout the water column; however overall the stream flow isn't chaotic. Considering channel morphology; such streams are characterized by a general broad U shape. This is important! Although discharge may be high, the open nature of the channel allows for high flow with little impediment. Such flow regimes are beneficial to aquatic vegetation for multiple reasons:

1) Low shear forces- Although shear stress is present in all natural fluid flow situations; eddies and other turblent flow instabilities are areas of high localized shear stresses. We see this in our aquariums when using spray bars. The flow nearest the outlet is very fast relative to the area around it. This differential velocity creates eddies and vortexes in which shear forces can cause plants to lift out of the substrate or which can tear leaves off the stem; thereby damaging the plant.

2) Chaotic flow (high Re) likewise creates zones of increased and decreased water movement. We see this characterized by zones of deposition and resuspension of mulm in our tanks. The zones of high flow receive good input of nutrients and CO2; whereas the zones with low flow may be deficient in one or the other. Likewise, the deposition of mulm can create zones of localized water quality instability and become a source of harmful chemicals.

Consider the placement of filter outputs for a moment. The convention of placing the filter outflow on the side of the aquarium rather than the back aids in the creation of laminar flow. *Why?* The increased length of flow helps to disperse the energy related to filter discharge. The farther the stream travels before hitting an impediment such as the side of the tank, the greater the impact viscosity plays in the flow dynamics. Conversely, if I put a spraybar or other outflow on the rear of the tank facing the front, the short distance between the initial outlet and impediment decreases the contribution of viscosity which causes an increase in energy when the flow hits the impediment. The higher the flow energy at point of impediment, the greater the Reynold's number, and the greater the turbulence of flow at the point of impact. 
Using the below equation we see the following:



















is the mean fluid velocity (SI units: m/s)
_L_ is a characteristic linear dimension, (traveled length of fluid, or hydraulic diameter when dealing with river systems) (m)
μ is the dynamic viscosity of the fluid (Pa·s or N·s/m² or kg/(m·s))
ν is the kinematic viscosity (ν = μ / _ρ_) (m²/s)








is the density of the fluid (kg/m³)
Given a constant viscosity, discharge velocity, and density of water leaving our filters; L, distance to impediment or width of stream flow is the characteristic which defines flow regime. If L is small, Re will be large. If L is large, Re will be small. Remember, we're multiplying L by two constants and dividing by another constant. The greater the pVL term the lower the overall ratio.

*What the hell does this mean for my aquarium?* In order to create an environment with the greatest potential for laminar flow we must set up a situation where either L is high or V (discharge velocity) is low. To use my aquarium as an example. I have spraybars placed along the substrate surface and tank sides which face the front of the tank (small L). In order to maximize laminar flow potential I have to decrease V. Assuming my pump is always discharging at a constant rate and the viscosity and density of the water leaving the spray bars is constant, I must either increase the size of the holes in the bar, increase the number of points of discharge, or both in order to reduce the Re.

*Why would I care about that?* Don't I want the highest velocity possible from my spraybar to suspend mulm so it can be picked up by the filter or transport it to a place where I can syphon it out? No!!!!!!! Remember, high V creates turbulent flow which, in turn, creates flow instabilities as discussed above. I want smooth, laminar flow to uniformly distribute water. This uniform flow distribution may be slower than turbulent distribution, but it is more effective in both nutrient distribution and removal of undesireable materials from the water column over the long term. Why?! Because laminar flow reduces differential zones of suspension and deposition. The greater the proportion of zones of suspension to deposition, the greater the volume of particles removed from the water column OVER TIME. This is the big secret and science behind the Lily Pipe and convention of placing the filter outlet on the side, rather than back, of the aquarium. Since stability is, by definition, a characteristic of change over time, one must consider efficacy over time rather than instantaneous or immediate efficacy. Turbulent flow can improve results in the short term, that's why we stir the water in planted areas at times when cleaning our aquaria. The instantaneous turbulence suspends the particles we want to remove. In general, however, this is not a desireable condition.


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## niko (Jan 28, 2004)

Honestly, the more I think about having the water move in a laminar pattern the more I think we maybe on to something.

The idea is to involve as many waste particles in the water movement. A laminar flow does seem to literally pull particles off the bottom and from any surface. Shrimp and otocinclus can only help suspend them.

I really liked that you make a serious point of the difference in the short and long term. I do not know if our ideas about laminar flow having more "cleaning power" are really true. But definitely the results will be seen in the long term.

Also the fact that with laminar flow we may not need pump to move 8-10 times the tank volume per hour. ADA's filter for the 180 gallon tank is moving only 3 times the tank volume an hour! How can that be the standard filter suggested by ADA? You are telling me that in my 180 gallon tank I can put a 460 gph pump and filter it fine? No way! Except maybe if the flow was laminar... Or if the tank was a very open aquascape with only carpet plants.

http://www.adana.com.my/products/filter_system.htm

This is getting exciting (despite the formulas) .

--Nikolay


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## Phil Edwards (Jan 22, 2004)

LOL, just wait until I post a discussion of shear forces.  :tape2::tape2::tape2: 


Don't forget Niko, the information you've found is mostly in reference to aquaculture where the goal is to produce as much fish mass in the smallest volume possible. That requires A LOT more filtration than does a decorative aquarium. It's still very good and useful information, we just have to take it in the context of our aquariums rather than a grossly overstocked system.


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## Ekrindul (Jul 3, 2010)

Some problems that keep bugging me I wonder if you could address, Phil.

How could we apply laminar flow to a rectangular aquarium where the outflow is so narrow and where the water must circulate rather than continue along a unidirectional path? Even with a spraybar, we cannot recreate the effect seen in a river where the flow is uniform. If we attempted to create laminar flow using either a spraybar or powerhead by extending the flow as far as possible before an impendment is reached, won't we always be creating the largest deadspot above or below the outflow?


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## Michael (Jul 20, 2010)

This discussion reminds me of river tank manifolds used by hillstream loach keepers.

I can also add from practical experience designing water features that the easiest way to decrease turbulence and increase laminar flow in piped systems is to increase the diameter of all the pipe. Aquarium circulation/filtration is designed with the smallest possible pipe--easier to conceal. But these small pipes increase turbulence, especially when the water is squirted back into the aquarium through a small-diameter opening.


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## Phil Edwards (Jan 22, 2004)

Ekrindul said:


> Some problems that keep bugging me I wonder if you could address, Phil.
> 
> How could we apply laminar flow to a rectangular aquarium where the outflow is so narrow and where the water must circulate rather than continue along a unidirectional path? Even with a spraybar, we cannot recreate the effect seen in a river where the flow is uniform. If we attempted to create laminar flow using either a spraybar or powerhead by extending the flow as far as possible before an impendment is reached, won't we always be creating the largest deadspot above or below the outflow?


*Laminar flow doesn't mean unidirectional flow.*

The definition of laminar flow is dependent on the kinetics and energetic state of the fluid. Up to a certain energetic state the viscous and kinetic properties of water resist turbulence; this is Laminar (not unidirectional) flow. As soon as the energetic state of the fluid goes above a threshold defined by the viscous and kinetic properties of that fluid, the flow becomes turbulent.

Likewise, flow in rivers is not uniform. The area of highest flow is somewhere in the middle of the channel whereas the lowest flow is along the banks and bed. The solid structures of the bank and bed create friction which reduces flow velocity (topic for another upcoming thread). A stream will have places where the flow is generally laminar and areas where flow is generally turbulent. However, even in an area that is generally laminar as defined by an appropriate Reynold's number there will be zones of turbulent flow due to the influence of friction and shear forces.

Remember, water flow is always in three dimensions except in insane theoretical circumstances. Even though the water in our tanks may be jetting out of a spraybar, the viscous properties of water will cause water from behind, above, and below the outlet to move toward the direction of strongest flow. *This is where lily pipes come into their own* They're designed in such a way as to maximize flow congruency in areas surrounding the outlet. In effect, the design of the structure maximizes the tendency of moving water to pull the surrounding water into the stream. Korallias and similar products, as well as penductors/eductors, capitalize on these kinetic and viscous properties to create mixing around the outlet.

This effect is reduced when using a spraybar as there are multiple outlets.

If you've ever put a floating toy on the water and caused it to move by dragging a finger through the water ahead of it; you've seen this principle in action.

Michael hit the nail on the head. Since we're pushing water through the smallest possible outlet we're increasing the velocity of water discharging from the outlet. If discharge (velocity times area) is constant, decreasing the area of the outlet increases velocity. That increased velocity is a result of concentrating the kinetic energy of the water as it passes through a compressed area.

Conversely, increasing the are of your outlet decreases the velocity and kinetic energy of the stream as it widens and the energy is diffused through a broader area. If we wanted to maximize the potential for creating laminar flow (it's in 3 dimensions, remember) we would have to create some sort of outlet structure which reduces outflow velocity enough to achieve a kinetic state which is below the threshold of turbulent flow.

This structure is also known as a Lily Pipe.  The more I think about all this stuff, the more I realize ADA has put some SERIOUS time and money into R+D and have paid a lot of energy into understanding topics such as fluid dynamics and engineering design as opposed to solely design/aesthetics.


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## Phil Edwards (Jan 22, 2004)

Cool visual of laminar then turbulent flow.






Low Reynold's flow (laminar) through a tight opening (aka spraybar). See how flow compression causes turbulence.






Demonstration of 3D water "pulling" from a lily pipe. The vortex is created by slower moving water being pulled into the faster moving stream leaving the lily pipe.






A great video demonstrating the same with riccia:


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## Ekrindul (Jul 3, 2010)

Phil Edwards said:


> Demonstration of 3D water "pulling" from a lily pipe. The vortex is created by slower moving water being pulled into the faster moving stream leaving the lily pipe.
> 
> 
> 
> ...


Yes, I see the same effect with my Koralias, but never with say a Hagen powerhead.


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## niko (Jan 28, 2004)

This discussion may seem pretty hard to read or even useless to someone. But I assure you - this, and a few other topics published here in the last several days, are things that we should have known 10 years ago. It would have propelled this hobby to a new level back then. At least something is moving now. So please check these posts when they are updated. The information found here cannot be found anywhere else. And it will probably change a lot in the way we setup planted tanks. This is only the beginning of something new. It will take a long time to establish itself.

So, to give you a simple visual impression of why we started discussing water flow rates and flow types I will remind you that most of us intuitively believe that the more flow you have the better you are removing the dirt from your tank. We also believe that the more jets you have scattered around the tank the better - they all move the water from a gazillion angles and the dirt has no place to hide. We have all seen (and some of us designed and used) elaborate manifolds placed under the gravel, Koralias all over, spraybars in every position imagineable and so on.


































On the other hand ADA uses a very simple and elegant solution. Sorry for the repetition, we have all seen a Lily pipe, but here it is - the same thing every single time:









So it is logical to wonder what is it that ADA knows and does that we, as a community, don't.

By closely looking at the operation the Lily pipe a few things jumped out. That is what is discussed in this and the other recent threads about filtration.

This post is meant to give you a visual impression of why we discuss these topics. Here's another visual - this time maybe hitting close to home. I believe many of us can literally look at their tank(s) right now and see what I'm talking about:

Yesterday I did a water change in my big tank and scrubbed a little alage from the Manzanita wood. Fine dust from the soft Manzanita blew everywhere, but I did not think much of it.

Today, a day later, I looked at the completely clear water in the tank. Yes the water is perfectly clear but there were still suspended particles of the Manzanita floating everywhere. In my effort to see if these are microbubbles of air or actual Manzanita dust I observed the particles for some time. I noticed that:

1. The particles were brown (so they were.. and are... wood)
2. The particles never settle! They dance around inside invisible boundaries! Endless suspension! I tracked one bigger particle and I saw that it moved around inside an area measuring about 10 sq. inches. It never settled, it never went to the filter, it just kept moving around. Along with thousands if it's finer siblings.

In that 180 ga. tank I have 3 Koralias, 2 filter outflows, and a HOB micron filter. Flow is about 1800 actual gph. But they are not enough to move all the particles into the filter. On the other hand they provide the tiny particles with opprtunities to be ground down to waste having an immense surface area. Wow!

Look at your tank. If you notice suspended particles that just dance around and never go anywhere you need to continue reading the posts about filtration and laminar flow. What you have is a nice factory for organics, waste and ever growing surface area of the trash you are recirculating and tumbling around.

Many people that have nice clean tanks will say that they are just fine with the water movement setup they have. But that doesn't mean that things cannot be streamlined and improved. ADA uses only about 450 gph of flow in their 180 gal. tanks. Try that with a nice big Eheim filter and you will fail. ADA has success with such a setup because they do things differently than what we know and believe.

Keep reading. Please.

--Nikolay


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## niko (Jan 28, 2004)

Phil, I leave you on your own here. Niko has left the building.

Some New Jersey or something guy in another thread got to me. Hope he doesn't respond to what I posted or PM me.

Right now I could care less if anyone is interested in knowing more about this hobby.

From now on my post will be as exciting as this:










--Nikolay


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## JustLikeAPill (Oct 9, 2006)

Why wouldn't an Eheim filter with a flow of about 450 gph on a 180 gallon tank with a lily pipe outflow work just as well as the Superjet filters? I don't see how you will fail just because you aren't using the ADA brand filter, which costs a fortune.

This is a very interesting thread and I will be re-reading it later. Very interesting ideas. I really see what you are saying about how laminar flow drags or pulls the particles.


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## AaronT (Apr 26, 2004)

JustLikeAPill said:


> Why wouldn't an Eheim filter with a flow of about 450 gph on a 180 gallon tank with a lily pipe outflow work just as well as the Superjet filters? I don't see how you will fail just because you aren't using the ADA brand filter, which costs a fortune.
> 
> This is a very interesting thread and I will be re-reading it later. Very interesting ideas. I really see what you are saying about how laminar flow drags or pulls the particles.


I think what Niko is saying about the SuperJet filters is that they don't lose gph as easily because they are rated for more power. In other words, the Iwaki pumps that are installed on top have a higher maximum head.

So if x brand of filter is rated at 450 gph with a maximum head of 8 ft and the y brand of filter is rated at 450 gph with a maximum head of 20 ft. the y brand filter will maintain it's near maximum flow for a longer period of time because it can overcome the clogging that occurs over time.

Think of it in terms of cars. If two cars have the same horsepower, but one has more torque, the one with more torque will still be able to accelerate at nearly the same rate even if some more weight is added to the car.


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## JustLikeAPill (Oct 9, 2006)

Gotcha!


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## Michael (Jul 20, 2010)

I'm still reading. . .and thinking.


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## Phil Edwards (Jan 22, 2004)

Michael said:


> I'm still reading. . .and thinking.


A dangerous combination, to be sure. :fish:


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## Bert H (Mar 2, 2004)

Very interesting reading here!


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## Michael (Jul 20, 2010)

Phil Edwards said:


> A dangerous combination, to be sure. :fish:


Yes, much safer and more comfortable not to read, or to think.


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## digital_gods (Apr 23, 2010)

If I understand correctly, the ideal situation is for the water to travel across the top of the column and than return to the bottom. I've attached my illustration to see if I'm understanding correctly.


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## Tex Gal (Nov 1, 2007)

@Niko - you must come back in. You got me with post #9. I have been reading the two threads eagerly. I have seen the ever floating dust in some tanks. I need to really take a look at my loops and make sure that I have them also as "closed loop" _inside_ my tank. It makes a lot of sense that not only may we need to think about dead areas as having no flow but also as dead areas with ever perpetual whirlpool flow. This can explain an ever constant battle with certain algae.

GOOD STUFF!


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## alta678 (Mar 24, 2009)

Niko, you got us all hooked (yes, I looked at all of those U tube videos) don't leave us hanging!op2:


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## niko (Jan 28, 2004)

Well, looking in the mirror, I have to say I do like my pouty face. But tonight I stumbled on something that everyone involved in the freshwater hobby must hear.

Especially if you are in the planted tank side of the freshwater hobby. And especially if you think Amano is a genius or just a clever marketer of cool looking glass filter pipes.

Here: A discussion on a reef forum about water flow and how it affects a saltwater aquarium. Started in 2006:

http://www.zeovit.com/forums/showthread.php?t=8740&page=2

On page 2 there are two things that hit close to home:

1. "...turbulence disrupts the boundary layer at the surface of a coral (facilitating higher nutrient uptake rates)..."

2. "...turbulence has the ability to transiently concentrate stuff in the water column..."

That tells us, planted aquarium folk, that we should know more about laminar/turbulent flow and how they affect our planted aquariums. It also tells us that we are way behind in our understanding of how the water should move in our planted tanks. Nice, eh?

From what I know abot the way ADA sets up their water flow they do try to avoid too much turbulence. I cannot say they are trying to achieve perfect laminar flow. But for sure the design of the Lily pipe now seems much more elaborate than I ever thought. I maybe way off in my thinking.

But we cannot deny that if the type of water flow has the ability to "facilitate nutrient intake" and "concentrate stuff in the water column" in a reef tank then we got to know how it all works in a planted tank.

It certainly feels like we are on to something new here.

--Nikolay


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## niko (Jan 28, 2004)

And please look at Jake Adam's articles titled "Water flow is more important for corals than light." parts I and II.

Freshwater plants are not corals, but once again - what do we know about flow, light, nutrition, and particles in our tanks.

--Nikolay


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## AquaBarren (Nov 6, 2009)

_"From what I know abot the way ADA sets up their water flow they do try to avoid too much turbulence. I cannot say they are trying to achieve perfect laminar flow. But for sure the design of the Lily pipe now seems much more elaborate than I ever thought. I maybe way off in my thinking."_

To my amateur points in my last post in the "other" thread.... Maybe what they know is that stable, laminar flow in an aquarium is impossible and therefore have designed an outlet that uses drag and vortex streets to its advantage, pushing them with acquired volume "down the street".

This seems like an optimal pattern. 




How could it be made a little wider? 
Keep all the vortices moving towards the intake and avoiding backflow? 
What role does high-pressure at the outflow side and low-pressure at the intake side play in this movement? Assuming there is a pressure variance of course. Just assuming there is.

Love this topic, wish I know more.


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## niko (Jan 28, 2004)

Did you see the description of Gyres (aquariums with very prominent unidirectional water flow) in one of Jake Adam's articles? Basically you put a piece sheet plastic in the middle of the tank. Either horizontally (like a shelf) or vertically (like a wall). Then you pump water only on one side of the shelf or wall. That creates a very pronounced flow going one way.

http://www.advancedaquarist.com/2007/1/aafeature

A horizontal gyre certainly makes me think of the way the water flows with a typical ADA Lily pipe setup.



















All that information is about reef tanks and corals. As I understand from the article with a Gyre setup you can actually create a lot of water movement with very little power (with a weak pump). The water gains momentum as it seems, similar to rocking a swing I guess. Maybe that's why ADA suggests a filter that moves only 2.5x the 180 gallon tank volume per hour - the dimensions of the tank are somehow optimal for the water to gain momentum with even a smaller pump. ADA suggest faster turnover rate in their smaller tanks.

In any case - this laminar/turbulent flow discussion is in place for reef tanks. Plants have got to differ in some way and definitely there is something to learn here.

--Nikolay


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## niko (Jan 28, 2004)

Someting else that has been "gyrating" in my head the last 2 days;

If you have to sweep the floor and there is a lot of very fine dust you are really better off moving the broom slower and using smoother sweeping motion. Fast movements make the dust airborne and are counterproductive.

Seems to me that the fine particles in an aquarium would be collected more efficiently if you don't swirl them around, making them fly all over the place. Also when the particles float around they grind or fall apart and turn into even smaller particles.

Since I too agree that complete laminar flow is impossible in an aquarum because of obstructions and maybe the square shape I start to think that the goal is to have both laminar and unidirectional flow. Laminar so the particles do not get banged around and grind themselves into smaller pieces. And unidirectional so the particles are constantly moved toward the filter intake - both pushed or pulled toward it. Like this:

Phil pointed out to me that the ADA intake is not only situated a little below the middle of the tank, but not close to the substrate but also it has a wide "intake" area. According to him that aids the water in maintaining it's flow as close to laminar as possible. Basically the Outtake shoots in an almost almost laminar fanning pattern close to the surface of the water, and the intake "pulls" in a wide pattern - the result is forming a "U" shaped flow that engages particles from the bottom and lifts them.

--Nikolay


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## niko (Jan 28, 2004)

There are 2 things about the flow that are pretty apparent if you have seen how the Lily pipe works in real life:

1. The flow pattern of the water coming out of the Lily pipe is like a fan. A fan spead under the surface of the water. Flat side up.

2. The water flow along the bottom is actually going up as it gets close to the intake. Now the fan is turned sideways - with the flat part toward the front glass. Because the water flow is going under an angle toward the intake, particles are lifted from the bottom.










That explanation certainly sounds like overthinking. But it may explain why ADA places the pipes close to the front of the tank - because there is at least some degree of "water flow twisting" that could be involving water+ particles from the back of the tank.

If that is really how it all works I'd say it's pretty ingenious - and implemented in such an elegant way.

--Nikolay


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## niko (Jan 28, 2004)

Tonight I have single handedly discovered one of Amano's secrets. Yes, no exageration. It's called "a gyre". Read on:

I just re-read Jake's article and here's what I think needs to be noted:

"..In order to maximize the output of water flow equipment, aquarists should design water movement systems so that all the components work together to minimize resistance and move the entire water mass of the aquarium. The best way to combine the energy of moving water to produce maximum water motion for an aquarium is to encourage the formation of a circular course of water movement called a gyre. Like the wheel, a gyre takes advantage of feedback mechanisms which preserve momentum by minimizing resistance. An aquarium gyre somewhat resembles a conveyor belt of water movement and it is characterized by *mostly laminar, unidirectional flow*..."

The placement of the ADA Lily pipe and intake certainly are following that advice!

--> The pipes are in the front of the tank, where the flow is not restricted (minimal resistance + preservation of momentum).

--> The pipes form a "circular course... called a gyre."

--> The pipes "work together to... move the entire water mass of the aquarium..."

And note this: "...An aquarium gyre ...is characterized by mostly laminar, unidirectional flow..."

Phil and I invented the wheel a week or so ago! We figured out these very things. Well known already.

I feel smarter than ever before! But I do believe that there is a benefit from all that comotion - eventually we will know more about how to make planted tanks more predictable. Hopefully.

Certainly makes me eager to make my own "gyre". I bet the explanation for all this is somewhere in numerous Japanese publications. It is beyond me why we here in the US, as a community, have never had access to these things. Or could it be that we never had interest?

Well, anyway, now we know a little more.

(A combination of EI and a gyre has got to be an explosive concoction worth mixing! I have a strong suspicion that Tom Barr knew that years ago!)

--Nikolay


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## AquaBarren (Nov 6, 2009)

I haven't seen a lily pipe in action in person. I do recall discussion that one of the benefits of the whirlpool that a lily creates is an immediate downward flow and that the intake was higher than typical to encourage a u-shaped movement of water in the tank...down from lily, along bottom then up to intake.

I just gave NY 8-year old a tank of her own -new fluval Studio 600. It comes plumbed from the bottom of the tank, with both intake and outflow adjacent and rear/left of the tank. The inlet is approx 1/3 down from water kine. The outlet a little higher, is a pair of jets at 90 degree angles that I have aimed to the right. The flow in that tank is much like the gyre you have depicted above. You can see it...sinking pellets follow that path. Sophisticated test eh?

It's a 24 x 17 x 18 tank, so outflow hits walls quickly. Can't imagine that arrangement would perform the same way in a larger tank. Seems intake undercurrent would eventually overcome outflow momentum and create an area of stalled flow on the opposite side of the tank.

Given that our tanks have stuff in them I can't see how that on-it's-side U shape can be achieved in a large tank. 

I tend to think of flow as a function of outflow force and shape. But I wonder what role pressure variance may play in the overall movement through a tank. Does the lily just establish a wide vortex street with a little downward force as fast as possible, depending on negative pressure to then pull through the tank?


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## niko (Jan 28, 2004)

This link:

http://www.ukaps.org/forum/viewtopic.php?f=21&t=11056

Contains a discussion that has a lot to do with what we are discussing here. Funny enough that thread was started on my birthday.

I don't see these guys talking about laminar/turbulent flow. Just flow rate and also relationships with other factors.

Because it's impossible to say that higher flow is always, every single time, better there are a lot of opinions. As I type this I have a 55 gallon tank that grows all sorts of plants. 54 watts of light, and cicrulation of about 30 gph. That tank never has any issues - CO2 or no-CO2, water changes or not. I have to remove handfulls of plants from it every 45 days or so. I never fertilize.

But once again - that's a case of "this works for me and I don't know why". What I'd like us to find is what works every time and we have more answers to issues.

--Nikolay


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## fishyjoe24 (May 18, 2010)

yep I always wondered why I would see journals of people drilling the side of there stand for the canister tubes and now I know why. if the canister hoses are coming from the back would the return just spray water to the front of the tank? going on the sides the spray bar can shoot to the other side of the tank, then on the other side a hydor korlia power head can circle and create flow back to the intake... to where the intake can pick up debree


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## Aquaticz (May 22, 2009)

I may just try that out fishyjoe24
Thanks everyone

Niko how is this being posted in mutiple places or various threads? Great stuff
Thx


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## niko (Jan 28, 2004)

Because the ideas kept coming Phil decided to make a separate thread with a more civilized title -this one. I still update the other thread. Both of them are in the DFWAPC sub-forum and that's an order good enough for me.

If one is interested in the topic of flow impoving their planted tank they will put the "effort" and find where the information is. 

--Nikolay


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## fishyjoe24 (May 18, 2010)

your welcome... speaking of hydor k power heads.. I saw nanos 240's might be the nano 425's on clearance at pet supplies for 23.97 and the k ones where 29.97 on clearance... coral-life 24 t5 normal out put light fixtures are 37.97 on clearance and the 48 inch t5 normal out put light fixtures are 49.97


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## JustLikeAPill (Oct 9, 2006)

I have been following this thread, and playing around with my own lily pipe. What really interested me was the discussion of the gyre, and how Amano typically puts his lily pipes toward the front of the tank.

I have never noticed it until you mentioned it, but you are right. He does tend to put his outflow toward the front of the tank.

I had my outflow dead-center on the side of the tank and so I had good laminar flow, but when I moved my pipe to the back of the tank I noticed how the water would still flow in the same manner as it was before (flowing from top, hitting the other side of the tank, flowing down, then flowing back to the other side, in a circular manner) and I knew that this was the way the water moved in the tank by watching the way the bubbles from my diffuser (placed on opposite side of tank) would move.

Now, the water ALSO flows strongly along the back wall of the tank, circling around and then moving traveling along the front wall and back to the intake. Like a whirlpool. In a whirlpool in nature you would expect a dead zone in the center, but I believe the design of the lily pipe (when placed along the front or back glass, creating this whirlpool) also "folds" the water creating laminar flow that continuously drags water through the center of the tank and preventing the center from being a dead zone, despite the whirlpool effect that seems to happen (IME) when the outflow pipe is placed towards the front/back glass.

I tried to draw a quick sketch in Paint to show what I am talking about. Please look at this picture and notice that this picture can represent a view of the water flow in the aquarium when looking from ABOVE, or when looking from the FRONT. The flow seems to take this pattern in both directions. It is hard for me to articulate the words to describe what I am seeing in my aquarium based on the movement/distribution of the co2 bubbles, so hopefully you guys understand. In a nutshell, I think that by placing the outflow on the front or back of the tank, a U pattern is created but this is a double U (water moving on top, down, along the bottom then up to the intake, as well as along the back, along the side, along the front, and then up back into the intake.) All the bases seem to be covered this way.


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## niko (Jan 28, 2004)

That was very intresting! I knew that once the flow is not turbulent there will be things that are not intuitive. I thought along the lines of the flow "pulling" particles from everywhere. But I never thought that the "U shape" of the flow would be the same vertically and horizontally. And on top of that - wherever you move the Lily pipe setup.

At this point I don't know if we are noticing things that Amano himself has not noticed. As I just described in the other thread after talking to Luis today it seemed to me that the original design and placement of the Lily Pipe and intake were as they are because of the CO2.

But we can't deny the venturi action, the aeration function, the surface scum sucking ability, and the flow that seems to really, really make sense in every dimension. On top of that the glassware looks way better than any plastic piping we know.

I'd say that now the question is not if we can create laminar flow, but "Can we create directional flow that does not allow particles to linger in the water column, distributes the CO2 well, and does not leave stagnant areas?"

It's pretty amazing how the Japanese have solved all of that (and more) with the Lily pipe.

--Nikolay


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## flashbang009 (Aug 6, 2009)

Another great thread to read through. A question that comes to mind when reading about the Lily output placement and co2 dispersal is how it changes when we diffuse inline with the filter output. It's been discussed that the Lily pipes are sometimes placed in certain places to pick up co2 from the diffuser on the opposite wall, but how does an inline reactor change things (if at all?)


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## dmartin72 (Oct 9, 2004)

Interesting stuff!

I have a 15 gallon tank with one of those Zoomed 501's, which I thought was not providing enough water movement and allowing surface scum to build up. I am going to play around with the placement of the intake and outflow tubes while removing the spray bar for a singular outlet. This should be interesting to see what kind of "gyre" I can produce with this rather tiny and weak canister filter. I'll report back later.

Also, I have dead spots in my 65 gallon tank and have been worried that EI ferts weren't getting distributed evenly throughout the tank. I'll play around with it tomorrow as well.

David


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## AquaBarren (Nov 6, 2009)

Here's a question that I've always wonders about. "how dead is a dead spot?"

Really, how dead IS a dead spot? O know, depends. I've always assumed that due to pressure variances in a tank water will circulate throughout. In "dead spots" that would mean slow movement, osmosis-like. But as long as there is good movement in the tank overall, isn't it likely that all plants get adequate exposure to co2 and ferz? They can only uptake so fast, so for plant health is a strong stream of flow in all nooks and crannies really necessary? 

The benefit of deliberately eliminating dead spots then is just to keep detritus off the plants? 

Just wondering. In my 84g i have had obvious areas of low flow, but the plants didn't seem to suffer.


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## AaronT (Apr 26, 2004)

AquaBarren said:


> Here's a question that I've always wonders about. "how dead is a dead spot?"
> 
> Really, how dead IS a dead spot? O know, depends. I've always assumed that due to pressure variances in a tank water will circulate throughout. In "dead spots" that would mean slow movement, osmosis-like. But as long as there is good movement in the tank overall, isn't it likely that all plants get adequate exposure to co2 and ferz? They can only uptake so fast, so for plant health is a strong stream of flow in all nooks and crannies really necessary?
> 
> ...


There is a filtration benefit as well. The same bacteria that colonize your filter also colonize the substrate, plants and hardscape.


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## Phil Edwards (Jan 22, 2004)

*AquaBarren,*

First off, I'd like to say how cool it is to have someone who works in the fluid dynamics field in on this discussion! :whoo:

You've brought up an interesting point about pressure differentials. I'm sure they're a factor at some scale in our aquariums; but I don't believe they're significant on the large scale. The reason being, in such a small (even a large aquarium being small relative to nature) and enclosed system, our filters or other water movement devices tend to equalize pressure throughout the tank.

This also affects osmotic regulation or movement of chemicals in an aquarium. Relative to the small differences in pressure or concentration, circulation is so great as to make any osmotic gradients or pressure differentials insignificant, except perhaps at the plant-water boundary layer. I don't have any data to back this up; but I have observed greater plant health and growth in areas with stronger circulation vs weaker, in personal aquariums with non-uniform circulation.

"Dead spots" certainly aren't dead in the biological sense; rather, they're "dead" in regards to circulation. I've noticed a distinct increase in cyanobacteria and some algae in these dead zones. In my experience and opinion, what's good for algae is bad for plants, making dead zones a bad thing.



> But as long as there is good movement in the tank overall, isn't it likely that all plants get adequate exposure to co2 and ferz? They can only uptake so fast, so for plant health is a strong stream of flow in all nooks and crannies really necessary?
> 
> The benefit of deliberately eliminating dead spots then is just to keep detritus off the plants?
> [/quote/
> ...


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## JustLikeAPill (Oct 9, 2006)

So I moved my lily pipe from the back towards the front and noticed something cool. The co2 distribution from the diffuser on the other side of the tank is just as good, and by looking at the way the bubbles move I can see that the "whirlpool" type of flow makes water flow faster on the BACK glass of the tank and before, when I had the outflow in towards the back, the flow was strongest on the front glass and the waters pretty much went OVER the stems in the back, hit the other side of the tank and swirled around and flowed back, giving the foreground much more flow than the background. Before, the majority of the co2 bubbles were above my HC foreground, and now the majority of them are flowing through the leaves and amongst the stems of my background plants.

It seems to me that Amano chooses to place the intake towards the front pane of glass for the above reasons. Putting it towards the front gives much more flow in the back of the tank, making water flow through the stems and distributing co2 and nutrients and preventing detritus build up MUCH better when the outflow is placed toward the front rather than towards the back.

Placing the outflow of the lily pipe in the dead center doesn't create this "whirlpool effect" that I have noticed. It does not make a "double 'U'" pattern, only a single "U". 

I just thought this was interesting. I am keeping my lily pipe towards the front. It works much better if you have stem plants in the back.


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## niko (Jan 28, 2004)

One more observation about good flow and (pretty surprising) plant health:

In this tank:
http://www.aquatic-plants.org/gallery/javafern55

I had a lot of Java Fern. Apaprently. It was really dense - like hard cabbage leaves stuck together. You can see the exceptional health of the plant.

What is interesting for this discussion is that in that tank I had a spraybar running along the bottom of the tank. It was in the back shooting water forward. When I took the Java Fern out of the tank I was pretty shocked to find out that all the leaves on the back of the tank were fresh green. There was no difference between the leaves close to the light and the leaves living in complete 24/7 darkness in the back of the Java Fern bush and close to the bottom.

I attribute that to the fact that those leaves were the closest to the spray bar. Also the flow went under the Java Fern bush and up. Basically engulfing the entire plant as a sheet. On top of that the excess P really made the Fern happy. But it does appear that the perfect flow probably had to do a lot with the plant's exceptional health, especially where there was constant darkness.

The tank on the pictures is 4' long. The Java Fern taken out of the tank was placed on a 6' table. It stretched 6' long and it was about 8" thick laying sideways. That's A LOT of plant. And every single leaf was as green and beautiful as on the last picture:

http://www.aquatic-plants.org/gallery/javafern55/DSCN3516_1

--Nikolay


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## niko (Jan 28, 2004)

JustLikeAPill,

Do you mean that placing the flow dead center on the side glass did NOT create the whirlpool effect? Or it DID create the effect?

"...Placing the outflow of the lily pipe in the dead center does create this "whirlpool effect" that I have noticed. It does not make a "double 'U'" pattern, only a single "U"...."

--Nikolay


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## JustLikeAPill (Oct 9, 2006)

Sorry about that, I meant doesn't. It does NOT create it IME.

I'll edit that.


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## fishyjoe24 (May 18, 2010)

wow nice that was a nice tank just use the java fern.. how much java fern did you start with, and how fast did it grow? did you have t12 t10 t8 or t5 lighting normal or high out put? I guess when it says 2wpg to 4wpg it was t12? also when you say "P" you mean potassium right ?


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## Phil Edwards (Jan 22, 2004)

*JustLikeAPill,*

That's great info, thanks for sharing your observation. Do you have a camera capable of taking video? I'd be interested in seeing some fish food moving around in your aquarium.

Regards,
Phil


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## JustLikeAPill (Oct 9, 2006)

I have an ipod that records video, I can play with it today and see how it works. If it's crappy I can read the instructions on my sony cybershot and see if that works better. 

I don't actually own any fish food since I have no fish. Maybe I can turn down the flow and use food coloring to show where the water moves?


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## Aquaticz (May 22, 2009)

Hey Phil & All,
Really loving this thread. last week I started to increase flow through an eheim cannister filter on a 55 gal tank. I did so by changing out the media to lava rock that was purchased at the home depot. 
I left the lower tier of old media & plan on removing the balance this weekend with more lava rock. I have already notice increase flow & the tank is clearer but still not crystal clear. I purchased some polishing cloth at the LFS (24 X 36). I am going to cut it to probably three times the diameter of the cannister,wad it up & stick in the top of the filter. I have been fighting algea...lol what a surprise <g>!

I also took Joey's suggestion and moved my already cut in half spray bar, the one furnished with the filter & moved it from the rear of tank to the side of the tank , the side with the inlet&with the end cap on the spray bar. 
This time I pointed it up a bit so it rippled the water a bit. Then I took a Koralia (think its a #1, I had a #2 but it was way to strong) & relocated it to the opposite side (about 5" from the water syurface pointing to the mid point of the tanks length. The result is much nicer, no more stems a blowing in the wind. I am thinking about down sizing the koralia as it is is sucking in some of the plant leaves due to its size.

I will take video with some fish food flying around so you can see the pattern. It is definetly an improvement. As a ::SIDE BAR:: maybe I'll get some sgae advice on my annoying *^$%&&^%$ algea. Notice I take ownership...LOL

Great Thread


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## Aquaticz (May 22, 2009)

I have a sony cyber shot the one that cost about 300 bucks- makes a great video compared to the 100 dollar version.
I'll post it later - off to get some otto's 

later gang


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## JustLikeAPill (Oct 9, 2006)

I tried taking video with food coloring since I don't have food, but it didn't turn out and my tank is blue.

The good news is that anyone can look at the flow themselves just by moving the lily pipe back to front, front to the back, to the center and experiment a little bit.


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## niko (Jan 28, 2004)

I expect layers of water moving with different speeds to color differently.

Could I ask you to add purple, orange, yellow, and neon green food coloring to the tank too. So we can track the movement really, really precisely?

--Nikolay


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## niko (Jan 28, 2004)

fishyjoe24 said:


> wow nice that was a nice tank just use the java fern.. how much java fern did you start with, and how fast did it grow? did you have t12 t10 t8 or t5 lighting normal or high out put? I guess when it says 2wpg to 4wpg it was t12? also when you say "P" you mean potassium right ?


Started with about 10 leaves of JF. Grew to that monstrosity in about 3 months.

Bulbs were Power Compacts, the tank existed in 2002.

P is for Phosphorus (K is Potasium).

--Nikolay


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## fishyjoe24 (May 18, 2010)

wow that fast. so 10 leafs grow to a 6 foot long table worth in 3 months, with you just using high light and phosphotus dozing, any other dosing?


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## niko (Jan 28, 2004)

Doesn't sound right but I guess it really grew that fast. I remember that I ordered the plants online from aquariumplants.com. You don't get "a Tex_Gal sized portion" when you order plants online. 

The Java Fern was part of an order of about 10 plant species. It all came in a box the size of 2 shoe boxes. So the Java Fern must have been no more than 10 leaves.

The first month I had the tank setup with "chat" - gravel used under roads, you can see mountains of it around every road construction site. The chat released tons of Ca and some plants grew 6-8" in about 8 hours. The water was milky from the Calcium and a thick dirty looking foam was on the surface at all times - flocculation basically. So I guess the Java Fern grew super fast too. I tore down the tank after a month - after someone told me how CO2 makes the Ca from the substrate disolve into the water.

Anyway, back to flow now. After 6 days without changing water in my big tank, feeding the fish very heavily, and seeing abot 5 gallons of evaporation (it's very dry now in Dallas) I finally start to see some Cladophora creeping up. The Bolbitis has been growing very well with all that flow + I guess a little dirtier water. BBA does not even try to come back.

I'm still to organize my flow to form the "U" along the front glass that we all agree is probably a special kind of pattern that works wonders. But so far just increased flow has made a big change to my big overstocked tank with only 1 kind of plant in it.

--Nikolay


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## AquaBarren (Nov 6, 2009)

"First off, I'd like to say how cool it is to have someone who works in the fluid dynamics field in on this discussion! :whoo:"

Thanks Phil. I actually just work in sales for a major tech company. We have a division specialized in data center design and optimization. Fluid dynamics modeling is one component of what they do. I sell that service among everythin else, so I know a little about it, but I'm a real lightweight, not expert for sure.

Your comments make sense...the flowand pressures created by our equipment would make everything else irrelevant in scale. 

Any thoughts on use of wave makers to create an occasional surge to and a wave of turbulence through a tank. I hate the look of waves lapping back and forth in a planted tank, but use of occasional pulses of a large volume of water as an alternative to elaborate outflows seems interesting.


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## AquaBarren (Nov 6, 2009)

Wouldn't have guessed this was a fluid dynamics model.

Ever hear of Saturn's hexagonal storm in it's north pole? I just learned of it. Very interesting and I wouldn't have thought possible in nature.

What do I know, can't even figure out an aquarium.

Check it out here:
http://www.tjmitchell.com/stuart/saturnrosslyn.html


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## fishyjoe24 (May 18, 2010)

AquaBarren said:


> Wouldn't have guessed this was a fluid dynamics model.
> 
> Ever hear of Saturn's hexagonal storm in it's north pole? I just learned of it. Very interesting and I wouldn't have thought possible in nature.
> 
> ...


8) what a awesome read, thanks you for posting that..


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## Tex Guy (Nov 23, 2008)

Here is a link to a PDF of the content from the most recent ADA book regarding filtration. The last 2 items are from their catalog on filters.

https://dl.dropbox.com/u/1657934/E-hOU.pdf

It's 2.5 mb


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## niko (Jan 28, 2004)

Tex Guy!

Wonderful information!

I see that you or someone else has been converting the metric units into Imperial. To figure out the ratio of flow suggested by ADA to the size of the tank. For everyone that has not followed this discussion closely - when using their proprietary filters ADA suggests pretty low ratio of tank volume to filter flow. That is because of 2 reasons:

1. They use special pumps that do not easily reduce the flow if the filter media clogs up.
2. They place the inflow and ouflow pipe in a special, very precise way, that makes the water in the tank move very well.


And if someone missed that - note that in the filter they DO NOT use any mechanical filtration. No coarse of fine filter pads. Never. Biofiltraton rules according to ADA. Of course - and reasonably at that (the biofilter is not established yet) - Activated Carbon is used in the first 1-2 months of the tank life. 

This wonderful information that Tex Guy posted has no explanations why. I think that in the last few months we here have discussed and understood quite a bit and can now follow ADA's advice with great understanding. Someone asked me just yesterday if the last few years of hanging out on forums has lead me to any kind of better understanding of this hobby. I think we will all agree - with this thread and a few others we have indeed learned something.

I personally really feel that I'm now capable of starting a tank and keeping it clean every single time. My desire to learn to do that dates back to about 2003. At some point I had lost hope that I will ever know. I saw a few people that were as obseesed as I was about finding "Amano's secret" just disappear from the hobby because it seemed so frustrating. I hope that everybody reading this thread appreciates the infomation that we all finally pieced together. As Luis Navarro and Jeff Senske always said - "There is no secret." It's all common sense really. And it is not Amano's single handed research and experience. One just needs to be open to look and find the knowledge.

--Nikolay


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## JustLikeAPill (Oct 9, 2006)

Actually the Bio Rio that Amano uses is REALLY good at capturing debris, even the silt when aquasoil is stirred up. I replaced all my media with Bio Rio for that reason. It compacts and catches a lot of debris but does slow down the flow a bit. 

I only use Bio Rio (and purigen on top) in my ecco. I do have a coarse filter pad on bottom but that is only so the bio rio doesn't fall through the bottom tray (it's pretty small.)


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## niko (Jan 28, 2004)

I found some old pictures of one of my first high tech planted tanks. I have talked about that tank - the one with the extremely healthy Java Fern in it. The picture of Java Fern that you have probably seen somewhere on thenet came from that same tank. The plant is not Photoshopped at all. The background is made blacker than it actually was, that's it:










On this picture you can make out the spraybar in the back:









So on the pictures I just found something pretty amuzing. The tank was basically a Gyre indeed! The very thing we discussed here few weeks ago. The water flowed out of the spraybar that was placed on the bottom, at the back glass. From there the water moved forward under the Java Fern roots. Then the water went up and to the side to the intake.

Besides the Java Fern the tank had only very short hairgrass that barely grew because the Fluorite substrate was new. There were also two Crypts which also barely grew. So nothing blocked the good flow pattern.

As I said - that was a 4' long 55 gal. standard tank. When I pulled the Java Fern out of it I laid it on a 6' long table and it stretched from one to the other side. A strip of Java Fern 6' long and 8"thick! Every leaf was completely healthy too.

Since I have very much posted all the above information already in this or other threads here's the new and strange part - the flow on that tank was very little. Smallest Hydor canister filter. Something like 160 gph. Add the hydrostatic head, the 90 degree elbows for the spraybar.. and I bet the flow was something like 50 gph if so.

So I believe that the open layout of the tank allowed for very good flow pattern and almost 10 years later I think I have it figured out.

--Nikolay


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## endgin33 (Jun 10, 2008)

This has been a find... Especially the illustrations of flow, grye, and the u shapes. They have really hit home. I recently made a mistake in the hardware arrangements on a long low tank (a GLA 91-B) than I think has an incorrect flow pattern. I hand bent some acrylic tubing to make a spray bar flush to the right end the tank with a spread pattern aiming toward the left. I built an intake with acrylic on the left hand side of the tank in the rear. I then hooked up an old monster 404 fluval to the pile and just prayed I wouldn't blast the substrate off the bottom. I figured that the filtration would flow smoothly from one side to another and the tank would have distinct flow patterns. Instead it stalls out and has built up a pile of protein scum on the left side surface that I wouldn't have expected. Even with the slightly unusual dimension's of such a flat tank I am now thinking I will be much better served with the Amano style setup. Any thoughts before I go thru the work of re-engineering the the stand and the acrylic?


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## niko (Jan 28, 2004)

Best thing to try that anyone can suggest at this point is to emulate ADA's placement of the pipes. That's the best starting point.

In the past I have tried huge flows and was always surprised to see that they did not take care of all the trash in the tank. I always assumed that with a lot of flow you can clean anything. That is not so. Flow pattern is REALLY important. It's somewhat amusing that we are starting to understand that just now.

--Nikolay


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## AquaBarren (Nov 6, 2009)

Btw, the book of ADA was free from Aquaforest. I did buy a bag of powersand, so maybe it was free with purchase, but I don't think so. Worth having.


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## Brilliant (Jun 25, 2006)

niko said:


> Best thing to try that anyone can suggest at this point is to emulate ADA's placement of the pipes. That's the best starting point.
> 
> In the past I have tried huge flows and was always surprised to see that they did not take care of all the trash in the tank. I always assumed that with a lot of flow you can clean anything. That is not so. Flow pattern is REALLY important. It's some what amusing that we are starting to understand that just now.
> 
> --Nikolay


Sorry to burst your bubble but of all my equipment I own a single powerhead and never purchased a flow accessory besides eheim plastic and ada style glass. Besides the fancy verbage I am trying hard to find the incredible breakthrough here. Thanks for breaking it down for the rest of us.


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## niko (Jan 28, 2004)

Brilliant,

If you think you have something uselful to say can you please retype the first sentence of what you just said because it makes no sense. 

This time do not start with "sorry to burst your bubble". It is a cheap insult and you know it.

I'm interested in the rest of the sentence and your experience. And note - I'm not confrontational.

--Nikolay


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## Brilliant (Jun 25, 2006)

niko said:


> Brilliant,
> 
> If you think you have something uselful to say can you please retype the first sentence of what you just said because it makes no sense.
> 
> ...


Apparently you were able to comprehend.

Now kindly explain in laymens terms what we have all been in the dark about for years. Ive read through the pages and can only see that elaborate flow setups are not as useful as imagined and single output is more effective. Am I missing something? If so I am interested in understanding what the big deal is all about. Thats all.


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## davemonkey (Mar 29, 2008)

How enlightening! I've been having some major issues with particulate matter in my new set-up, the 125 I got from mudboots. I recall him having the same issues when he had it.

I've got a canister filter and 2 powerheads (Koralia II and off-brand) and I thought I was getting the right movement. After reading this thread, I looked carefully and sure enough, particles were just floating all over the place, never settling, never making it to the canister intake.

I just now removed both powerheads and placed the canister filter output/intake at the end of the end of the tank as described for ADA stuff. I don't see the circular motion from top to bottom, but I do see it from front (water going forward) to back (water returning to intake). Probably I won't see the "Lily Pipe" motion because I don't have lily pipes, but it will be interesting to see in the next couple days if this helps with the particulate issue. (I'll let you know. )

I need to find the data on that filter so I know what ghp I'm looking at. My guess is that it is very low.
HERE it is. It says it pumps 250 gph.


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## niko (Jan 28, 2004)

Brilliant said:


> Apparently you were able to comprehend....


Apparently in your culture you constantly need to be cocky. Or you personally are that way. If you have something useful to say I'm interested to hear it and could care less how cocky you are. But so far I've seen only short bitter remarks.

What you are missing is so simple that it may sound like an insult. Once again - I'm not confrontational. Here it is:

*We do have some good understanding how to run planted tanks. But we often find ourselves asking questions without answers.*

That's it.

This thread and the 2 others that are connected with it now have about 5 000 views total. Keep in mind these threads are in a local club sub-forum. They would not get that much attention if there was no interest in this topic. Originally I wanted these 2 threads to be only in our local club sub-forum with the idea to boost interest among the members of our club. It turned out that the threads cannot be contained on a local level. I do not take the success of these threads as a triumph of my own puffy persona. I find that to be a proof that quite a few people would like to find more answers.

Am I missing something?

Personally I'm sorry, really sorry, that we, as a whole, are "discovering" things that some hobbyists have known and used for a long time. At least in the future we don't have to do that again. I hope. "Use Poret for quick filtration establishment", "Use Lava Rock for long term filtration", "Place the pipes to the front", "Don't let the filter clog"... now it sounds simple. But 2 months ago NOONE had ever talked about these things in a way that it became common knowledge.

I'm not going to say "Where were you, Brilliant, 3 months ago and why didn't you explain these things to us?". I'm not going to say that because I hope you now understand what are my reasons to discuss these topics.

Thank you for giving me the opportunity to clarify all these things. It is probably useful for someone to see the perspective in all this.

--Nikolay


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## Brilliant (Jun 25, 2006)

niko said:


> Apparently in your culture you constantly need to be cocky. Or you personally are that way. If you have something useful to say I'm interested to hear it and could care less how cocky you are. But so far I've seen only short bitter remarks.
> 
> --Nikolay


If I wanted to insult you I would have typed something different.

I thought I was quick and to the point. Since Ive gotten nothing back in the form of an answer I will assume my thoughts were correct.

What you are explaining seem to be the fundamentals of setting up and maintaining an aquarium so yes its quite simple hence my comments. No offence man.


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## niko (Jan 28, 2004)

If you typed something insulting your post would have been deleted by the moderators. You should see what I wrote in a new post 3 days ago about the ADA contest judging and expectations. My post disappeared within 1 hour.

Here. Let's be constructive;

Brilliant, could you write your thoughts on filtration? Simple and clear.

I will not come back with some half-baked witty remarks. Or any remarks that are negative. That will kill this thread.

--Nikolay


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## Brilliant (Jun 25, 2006)

You have to understand I was under the assumption planted tank people were experienced aquarists. I never really thought someone would be starting the aquarium hobby with a planted tank right off the bat. You will have to forgive me for thinking we were all from the same heritage. You know golfish bowls or tanks with background, fake ornaments and colored gravel. 

Filtration is very simple.

Buy Eheim
Dont over-engineer your flow config
Use oem or buy fancy glass pieces


My intake has always been in the corner to be visually pleasing more than anything. It just so happens that thats an ideal place to locate the intake.

The output flow should roll the tank. I remember messing with my output years back now I always put it on the side of the tank. Its visually pleasing and more effective. I even put aquaclears on the side. 

Ive added a koralia to provide more flow once in an attempt to increase co2 throughout the tank.

The planted tank in itself is a filter. I dont really know how to explain how it works but let the natural filter do its job. Large water changes and man made filtration is counterproductive to the natural filter.


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## redFishblueFish (Feb 12, 2006)

So the title of this post caught my interest, as I just graduated aerospace engineering and want to find *some* way to apply my shiny new degree  Reading this post, I'm realizing how little I remember from the past four years.

I had a couple questions, though. Reading through the posts, I wasn't sure if there was the underlying assumption that either laminar or turbulent flow was better for the tank, or if that point itself was what was being discussed. If one or the other is better, could someone explain why that is? Is it in general better to have suspended particles, particles in the gravel, or do you want those particles filtered out? I assume that you would want the dissolved nutrients evenly distributed throughout the tank.

A couple posts caught my attention. One subtle distinction (not sure if it matters) is that a flow goes turbulent once a flow has achieved a high reynolds number (Re), but the turbulent flow itself doesn't have a high Re. There is no corresponding descriptor for turbulent flow, actually. Also, one thing that wasn't discussed (I don't think...sorry if it was) was the property of turbulent flow to "stick" to a surface better than a laminar flow. It's for this reason that airfoil designers sometimes actually want turbulent flow in some regions of an airfoil. This property might be relevant in considering the flow past leaves. The flow is much more likely to separate from the surface of a leaf if it is laminar. Another property to consider is that turbulent flow is an inherently chaotic process. This means that something like cigarette smoke is not (usually) a turbulent flow in the technical sense, though in the colloquial sense of "turbulent" it might be described as such. With regards to the coral vs plant discussion, if I understand correctly, coral is a colony of tiny polyps. Because they're a colony, they have no central means of distribution like a plant does. Thus, each polyp must have all its nutrients flow past it, whereas a plant uptakes many of its nutrients through its roots (but not CO2, I believe). That would extend the discussion to what would provide good flow through the gravel. Another distinction that just came to mind was turbulent flow in general versus in the boundary layer. The boundary layer (region close to a surface) of a laminar flow is turbulent due to the imperfections of the surface. The thickness of the boundary layer is dependent partially on Re.

Phew...sorry if that wasn't useful, but it felt good to try to remember what I know. I'm about to start my first planted tank after five years of lurking but never having enough time to start a tank. Maybe I'll get to experiment with some flow properties!


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## Ekrindul (Jul 3, 2010)

redFishblueFish said:


> Thus, each polyp must have all its nutrients flow past it, whereas a plant uptakes many of its nutrients through its roots (but not CO2, I believe).


True with terrestrials, but aquatic plants are able to absorb nutrients through their leaves from the water column. Interesting read:

http://www.int-res.com/articles/meps/134/m134p195.pdf


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## digital_gods (Apr 23, 2010)

@redFishblueFish: If your using co2 injection, you want to run your flow below the boundary layer so you can use the surface tension to help keep the carbonic acid from releasing into gaseous carbon dioxide into the atmosphere.


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## Ekrindul (Jul 3, 2010)

digital_gods said:


> @redFishblueFish: If your using co2 injection, you want to run your flow below the boundary layer so you can use the surface tension to help keep the carbonic acid from releasing into gaseous carbon dioxide into the atmosphere.


Consider the discussion below on this issue. IMO, surface turbidity should be a part of every aquarium, as we should put fauna health first; flora second. Keeping a high O2 level is just as important, actually more so, than keeping a high CO2 concertration:

http://www.barrreport.com/showthread.php/8175-Too-little-O2-or-too-much-CO2-Please-help-me-make-sense-of-this.


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## redFishblueFish (Feb 12, 2006)

@Ekrindul
That was a fascinating read! They focused on phosphate and ammonia - I wonder if their results hold true for trace nutrients.

@digital_gods
I think we're using two different definitions of boundary layer. If I understand it correctly, you're using it to describe the boundary between air and water, whereas I'm using it in the fluid dynamics sense - as the boundary between a fluid and a solid. With air, at least, when you have a flow past a solid surface, the boundary layer is referring to the thin layer of air between the main airstream and the solid surface. The properties of that layer of air can be radically different than the properties of the surrounding air.


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## Ekrindul (Jul 3, 2010)

redFishblueFish said:


> @Ekrindul
> That was a fascinating read! They focused on phosphate and ammonia - I wonder if their results hold true for trace nutrients.


Unfortunately, much of the small amount of research there seems to be available on the subject isn't freely available. Hopefully, Phil will see this and enlighten us.

I've read that the bulk of nutrients in aquatic plants were collected by the root system, and also that the bulk of nutrients were collected by the leaves. I've read that the roots primarily function to collect carbon and anchor the plant. I seem to recall reading somewhere that iron transport in water hyacinth from root to leaf can take a few weeks to accumulate to a significant amount (would certainly point to an advantage for a plant that could collect iron from its leaves).

Seeing as plants cannot move when things aren't going well, it would seem reasonable that they would have evolved to have options.


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## dstrong (Feb 13, 2011)

I just read this entire post and it is very fascinating. It might be just me but I find designing a flow pattern to be mostly common sense. Just keep it simple, and it will be effective. Take powerheads for example, I personally feel that there is no place for them in most freshwater tanks, especially planted ones, unless you are running no filter and need it for singular movement.

Think about the natural environment. In a marine environment there is a LOT of turbulence around reefs cause by the water going rapidly from deep to shallow, e.g. waves. With the extremely large volume of a wave there is a lot of pushing and pulling of water in every direction. That's why reefers use so many powerheads pointed in every which direction and wavemakers on top of the outflow from the sump. They are attempting to emulate the corals natural environment on a generally very turbulent reef.

Now look at the typical freshwater plants natural environment. The current almost always flows in a fairly uniform direction, at a uniform speed. Typically there are no harsh cross currents or highly turbulent areas where these plants grow. If you think about a freshwater system, spring to end-point, it seems to me like a giant never ending train, one big continuous cycle. By the way I live in the most lake populous state (stick a sock in it Minnesota) so looking at a map I can see more lakes and river systems than I can count. Anyways what I'm trying to say is typically there is only one directions of water movement, forward. All there is, is where its coming from and where its going. Inflow and outflow. In this context it is easier to imagine the plants natural environment as a closed system and relate it to our own.

What you want, as has been previously mentioned, is one flow, in a loop, with inflow and outflow near the same point. This is as close to a magic formula as you are going to get, unless you want to build the same tank every time, and there is not fun in that. The rest of the details such as direction, flow rate and location are personal to your individual tank and are easily worked out on set up. Just observe and adjust. There are generally plenty of bubbles and other crap floating around in the water, just start with a high flow rate, find your location, find your direction, adjust your flow rate and your done. I feel that this is as close to the natural system as we aquarists can reasonably achieve, and it shouldn't take you 10 minutes. I usually find myself aiming the flow down the largest dimension of open water.

On the subject of laminar vs. turbulent flow, sometimes I find it is hard to have one and not the other. Take my 55 long for example. I was found it was difficult to get uniform flow *and* total tank coverage due to the length. What I ended up doing was taking the spray nozzle and aiming it directly across the middle of the tank. It was about 3 inch below the surface and blowing parallel to the water line. Once I adjusted the flow rate, it was *perfect* for my tank! The flow near the surface was of course a pretty turbulent but only a little past half way. When the water hit the other side it slowed a bit and formed a strong undercurrent that when to the bottom and then back across to complete the cycle. And wouldn't you know it, after the turbulence spread out I had perfect, even flow throughout the rest of my tank. The upper-left was turbulent, but the upper-right, bottom-right, and bottom-left were laminar. I also had no dead spots. Like I said though, this was perfect for MY tank. The tallest hardscape was maybe 7 inches and the tallest plants were probably 12, so they were unaffected by the turbulent top few inches, and my dannios *loved * the turbulent section. They'd sit there a swim head on into the outflow like it was nobodies business.

I love this thread and can't wait to read more on this.


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## redFishblueFish (Feb 12, 2006)

Ekrindul said:


> Unfortunately, much of the small amount of research there seems to be available on the subject isn't freely available.


Do you have names of articles you'd like to take a look at? I get access to a lot of databases through my university. Please, not too many though (I'm a busy grad student)  But feel free to send me some article titles that you think would be useful and I'll see if I can post them.



dstrong said:


> The flow near the surface was of course a pretty turbulent but only a little past half way.


Just wondering, how did you determine that it was turbulent? Did you use food dye or just observe particles in the flow?


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## redFishblueFish (Feb 12, 2006)

I actually read (ok...skimmed) a few interesting articles after my interest was piqued.

*Effect of boundary layer transport on the fixation of carbon by the giant kelp Macrocystis pyrifera*
I couldn't find this one in the databases, but I'll try again tomorrow. The abstract contained this interesting statement, though:


> "Experiments in water tunnels indicate that the boundary layer adjacent to the M. pyrifera blade may be turbulent in water speeds as low as 1 cm sec-1. Photosynthetic output of the blade can be increased by a factor of 300% by increasing water speeds over the blade surface from 0 to 4 cm sec-1. This is consistent with a decrease in the thickness of the boundary layer. Above 4 cm sec-1, the assimilation of carbon was limiting."


*Velocity gradients and turbulence around macrophyte stands in streams*
http://www.mediafire.com/?a9dvlukzg7czwbn


> Turbulence was maintained in the attenuated flow inside the plant canopies, despite estimates of low Reynolds numbers, demonstrating that reliable evaluation of flow patterns requires direct measurements.


You can't trust your intuition as to if it's laminar or turbulent - you have to measure the flows. This article talked about how the plant beds alter the flow. The flows can become more OR less turbulent depending on plant bed characteristics.

*Beyond light: physical, geological, and geochemical parameters as possible submersed aquatic vegetation habitat requirements*
http://www.mediafire.com/?bzw1tng221vgjag
This had a TON of awesome information. For example:


> Production of turbulence within the vegetation is dominated by the plant wake rather than by the bottom boundary shear, as in open channel flows (Nepf et al. 1997).


meaning that in streams and rivers, the turbulence is caused by the shear forces with the channel bed, whereas it was caused by the plants themselves in lakes (where the flow is due to wind driven waves). Also:


> The optimal turbulence levels for SAV is yet unknown but it is interesting to note that most SAV beds tend to occur in areas where flow is characterized by the laminar-turbulent transition (Ackerman 1998)


meaning it might be best for the flow to start out laminar but transition to turbulent as it hits the plants! There's a lot more to dig out in this paper, but I don't have time to read the whole thing. Someone please post any more interesting bits if you have a chance to read more.


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## dstrong (Feb 13, 2011)

redFishblueFish said:


> Just wondering, how did you determine that it was turbulent? Did you use food dye or just observe particles in the flow?


When I set the tank up I didn't wash the substrate very thoroughly and there was a lot of particles. (some really dirty gravel I bought at Stein's) Also I had quite a few tetras and some dannios so when I fed them I'd stick a decent sized pinch of flake under water right above the nozzle. The food would hit the blast from the nozzle and I could watch it do 3-4 laps around the aquarium before they would eat all of it. So I've spent a lot of time inspecting the water flow of my tanks. In fact I spend a lot of time in general with my nose up to the glass inspecting one thing or another, some might say too much time Haha.

Crap and I just noticed this.. In my post I used the word "turbulence" a lot, only it wasn't always in a technical sense such as the definition of "turbulent flow", and I never differentiated between the two very well. I hope you catch my drift:biggrin:


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## niko (Jan 28, 2004)

I'm writing this in an effort to remember it by re-wording. My learning effort maybe useful to someone else. Here it is:

--------------------------------------------------------------------------------------------------------------

First off, what is a "Boundary Layer"?

Google:
*Boundary layer: The layer of fluid that sticks to a solid surface and through which the speed of the fluid decreases. *

RedFishBlueFish's quotes say that:

- I cannot maintain only laminar flow in an aquarium. 
- I do not need to maintain laminar-only flow in a planted tank. 
- It is best to have a transition - the flow starts as laminar and turns into turbulent.
- There is optimal flow. It is a range (not a specific number). The range is 0 to 4 (some units)
- Within that range the plants can seriously increase their growth. (0 - 300%)
- Flow that is too fast can actually stop a plant's growth.

All of the above statements have to do with this "Boundary Layer" thing. But the only thing I can adjust are the pumps. All I can do is increase, reduce, and direct the flow.

--------------------------------------------------------------------------------------------------------------

My smartest approach for now is to find videos of tanks that show healthy growth and no algae. And watch for the flow in these tanks - speed and direction. So far I've noticed that ADA's tanks often (but not always) seem to have many plant leaves gently moving from strong flow. From what I read above it looks like it is pretty hard to say if a flow is laminar of turbulent just by looking. I also think that it is hard to say how strong a flow is by just looking. Especially on videos. But once again - it appears that if I make the leaves of my plants gently move in the current I am doing something in the right direction. And there is more to be done. Hopefully with this and other disussions we can find it.

And I will not be surprised at all if the general conclusion on what is optimal flow speed & direction in a planted tank are not far from what Brilliant said above - "very simple".

--Nikolay


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## niko (Jan 28, 2004)

RedFishblueFish,

From the quote below you conclude that is is best to have a transitional flow in a planted tank. A flow that starts as Laminar and turns into Turbulent.

What is "SAV" here?

_"The optimal turbulence levels for SAV is yet unknown but it is interesting to note that most SAV beds tend to occur in areas where flow is characterized by the laminar-turbulent transition (Ackerman 199...)"_

--Nikolay


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## Michael (Jul 20, 2010)

SAV = submerged aquatic vegetation


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## niko (Jan 28, 2004)

Here's a cheap (actually costing nothing) hack to achieve a resemblance of a laminar flow:

1. Install and HOB filter on the tank. Best placement - on the left or right side glass. Run it as normal.
2. Setup a second filter - a canister filter. Place the outflow pipe in the HOB filter box. (Place the pipe in front of whatever filter bag is used by the HOB filter.) Place the intake on the same glass on which the HOB filter is hanging.

That's it.

You get a very pronounced U-shaped flow with the HOB anyway. Adding the canister filter flow to it only helps. And it does not counteract the main U-shaped flow in any way.

A predictable thing that you will notice is that your 80gph HOB filter moves more water than the 160 gph canister filter. The main water movement is from the HOB filter. Good thing to remember when looking at flow rate of canister filters - most of them don't even come close to what is written in the box.


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## Chalcosoma (Sep 14, 2012)

*Re: Discussion of laminar vs turbulant flow - Experiment*

Hello everyone

I have been reading this old thread with interest. Right now I am trying to establish a slow, unidirectional, laminar flow from one side of my 400L tank to the other using a manifold design, similar to the hillstream approach but with a submersible Eheim pump instead of powerheads. And with a gentler flow rate.

My plan is to use a series of eheim spraybars attached via u-bends into a kind of grid. I have no idea if this will work  It will not be elegant! It will have many a green pipe and black suction cup! But hopefully I can conceal it with some roots and rockery.

The overall intent is to emulate a coastal stream in Cameroon complete with appropriate fish, inverts, and plants. The streams are neither rapids, nor sluggish. Can it be done? Stay tuned...


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## niko (Jan 28, 2004)

niko said:


> Here's a cheap (actually costing nothing) hack to achieve a resemblance of a laminar flow:
> 
> 1. Install and HOB filter on the tank. Best placement - on the left or right side glass. Run it as normal.
> 2. Setup a second filter - a canister filter. Place the outflow pipe in the HOB filter box. (Place the pipe in front of whatever filter bag is used by the HOB filter.) Place the intake on the same glass on which the HOB filter is hanging.


I've had about 45 days of observations with that kind of setup. It's a 30 gallon tank at my church. The canister is an Eheim.

The tank has no plants. Just 3 small fish and funky blue color gravel (tank is in the kids area). With a once a week 30% water change there no algae developing on the glass or equipment. One place always develops algae - brown dust looking algae develops on the gravel only (no tuffs or strings). The light is only a 15 watt fluorescent which I will soon replace with a T5HO.


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## niko (Jan 28, 2004)

Today I got around to hooking up the second big external Eheim pump to my 2 canister filters in a 180 gallon tank. I have the outflow hoses from the canisters plugged into a larger diameter U-shaped acrylic pipes (normally used for overflow boxes).

The flow coming out of the U-shaped pipes does look as close to laminar as it could be with such a setup. The water coming out of the U-pipe looks like acrylic itself - a completely silent smooth pillar of water. Except that is shoots straight down. I'm headed to Home Depot now to find a metal spring and try to heat and bend the end of the U-shaped pipe to an L-shape. Hopefully this will keep the "laminar" flow.

I attached a 90 degree PVC elbow to the end of one of the U-pipes. The water flow shoots out in a chaotic stream and makes a noise. Certainly far from laminar.

I am not hellbent on this laminar flow. I believe that as long as the water in the entire tank moves well you are good to go. The smoother the movement the better because then the water acts as a single body and could pull debries better - that's hard to deny.


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## UltraBlue (Mar 8, 2011)

Good discussion on flow patterns. 

I have a quick question for those who have looked at the flow patterns extensively. I currently have my lily pipe outflow on the front left corner and the intake on the rear left corner. Would it be worth drilling another hole in the stand to move the intake next to the out flow on the front corner?

Thanks for your thoughts.


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## niko (Jan 28, 2004)

Allrighs so I did the DIY acrylic bending and ended up with two U-shaped pipes with each end of each pipe pointing along the surface of the water. Think if it as a lily pipe without the lily.

The flow is very smooth. Not as smooth as coming out of the U-shaped pipe without the additional bent but I guess that is as close as it can get to smooth. Now I have 1000 gph actual flow in a 180 gallon tank. The tank is actually 160 gallons without decoration but Oceanic calls it a 180. So my flow is 6 times the tank volume per hour.

Both acrylic outflows are placed on the left side of the tank and close to the front glass. The tank has been drilled for 2 intakes on the bottom - in the left and right corner. I'm not going to change that for now.

UltraBlue,

The way ADA sets the flow pattern is both by the placement of the ouflow and the inflow. Look here:









The red arrows are the water flow along the front glass only. Someone did an experiment with suspended particles added to an ADA tank and they found that there is a U-shaped flow on the surface of the water too. In the current thread we have very much accepted that this double U-shape of the water flow engages water from the back of the tank too IF the current is smooth AND strong enough. The flow is both smooth and strong in an ADA tank. Placing the outflow and the inflow close has a synergistic effect (it multiplies the result without adding any extra effort) - it creates the strongest possible smooth U-shaped flow along the area that is normally free of plants and decorations - the front glass.

The essense of this thread is how to get the water flow smooth because this is a logical conclusion if you watch how the debries are being moved from all parts of the tank toward the intake. A chaotic flow does not engage the debries in a directional movement. And once again - the flow must be both smooth and strong.

Note also the yellow dots with short arrows on the picture above. These are debries that need to be moved toward the intake. Because the ADA intake is placed a little above the substrate there is a slight upward movement of the water along the bottom. This "pulls" particles out of the surface of the substrate and lets them engage in the flow toward the intake. Except that from what I can say now observing a tank without plants only the tiniest particles can be moved upwards that way. I now believe that Amano shrimp have the role of "shaking up" the larger particles, dislodging them from the susbtrate and make them suspended. Amano shrimp are pretty rough little animals and you can often see that they raise small bursts of dirt around them.

And to answer your question: You don't need to change everything in your tank to match ADA's setup. ADA has taken old knowledge and presented it in a cool and modern way. But that does not mean that you have to do everything exactly as ADA does it. As long as you engage the water from all over your tank in a smooth flowing movement you should be good. And if you are not - see if you flow rate is enough, see if dense plant tuffs keep the water from flowing good. Move the intake a little here and there before you install it like ADA suggests. It is hard to beat what ADA does but if you understand why they do things you can tweak them any way you like.


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## AquaBarren (Nov 6, 2009)

This isn't a perfect gyre, but moving the spray bar to the side accomplished a nice u-shaped flow in my tank. I made this change long ago after the discussion here.

In this video, I drop some small, sinking pellets into the tanks. You can see then move left->right, bounce off the right side and down and right->left.

It doesn't really show up well in this phone video, but I tried to follow some of the particles along the bottom of the tank back towards the intake side.

Not the double-U that a lily pipe can make, but better than a front-to-back arrangement.


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## JustLikeAPill (Oct 9, 2006)

I have a mini-m and a superjet ES-600 (After owning one, I love the superjets!) even though the filter is only about 100 gph, the flow was way too intense with a mini lily pipe. I switched to an off-brand lily pipe to decrease the flow, but it still moves the aquasoil on the opposite end of the tank.


If just ordered a 45-P since I wanted to upgrade anyway. If the flow is still too strong, I am considering being a guinea pig and ordering the new lily pipe spin, which is a circular pipe that releases water on both sides. It looks like a tire. 

I was wondering how this would positively or negatively affect the flow. It can't be bad if ADA releases it. OTOH, maybe flow doesn't matter that much on small tanks when you are using superjets?

I could order the new superjet es-300, but I can't justify spending $400 or so bucks when my es-600 holds six liters of media and the es-300 holds three and is only 50 GPH. 

I am hesitent to use a tap connector to decrease the flow..would it negatively affect the Iwaki pump?


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## David Lund Photography (7 mo ago)

Phil Edwards said:


> Hey y'all,
> 
> Niko and I had a really stimulating talk the other day about flow regimes in planted aquaria and it got me thinking. His example of laminar flow in the San Marcos in a previous post is awesome and I thought I'd expand on it a little. After keeping planted tanks by rote for so long, having a deeper understanding of the science behind what's going on in my aquaria has helped me immesurably. I thought I'd talk a little bit about what I've learned in the hopes it'll increase your understanding of your aquaria and improve your hobby just as it has mine.
> 
> ...



Im a commercial photographer that specialises in liquids, far from academic, but find liquids fascinating to film and shoot. new on the site and not totally shaw where to ask this question? I have a fascinating shoot on where I need to create a very even on mass flow of water from the left side of the tank to the right. Im attempting to build a tall and wide laminar flow, so that the water form the pump in from the left is moving about 4 litres a second but is smooth, no vortexing. Reason for this is there are objects that are designed to move in very specific ways in water, so a even flow is essential to monitor the precise movement. 

Ill upload the design, build... Its a test. used a simple laminar flow jet before, but this is moving water on mass from the left to the right of a large tank and being sucked out from he right, and around it goes..

Any ideas - suggestions, very welcome. If your curious about my work, its www.davidlund.co.uk 

Thanks for your time. I should be filming some Behind The Scenes which I can share.

David


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