# How to setup proper water flow



## niko (Jan 28, 2004)

Someone asked me in a private message. I typed it black on white, honest to goodness:

The proper flow pattern is something much simpler than we all think. Actually it has been used for decades now. But in the planted tank community most people fall for cheap tricks and forget to use common sense. Here it is:

1. The best flow type is laminar. That means that the water in your tank should not flow around in a chaotic way. It is best if it flowed like a wide and powerful stream. But that is impossible to do in a tank that is rectangular.

2. The best way to suck the water into the filter is when the intake pipe is a few inches ABOVE the substrate. That creates an angled flow along the bottom. That means that waste from the bottom tends to be lifted up. Not just move sideways as in the case when the intake is very close to the bottom.

3. Any cheap hang on back filter employs (1) and (2). It places the intake above the substrate and it has a very wide and smooth outflow. But in the planted tank hobby we needed Takashi Amano to tell us what is right. He just re-packaged what people have been doing for a long time. The cheapest HOB filter does exactly what a Lily pipe + the special intake glass pipe do. But an HOB filter is ugly.

4. Your flow should be circular. Imagine one circle starting from the outflow and ending with the inflow.

5. The circling water needs to hit as little obstructions as possible. There is only one way to achieve that - you direct the flow along the front glass. Normally there are no decorations/plants right against the front glass.

6. There is an unexpected result of that unimpeded circular flow. The water from the entire tank gets involved in the moving circle. You are now sucking water from behind rocks, wood, plants. It's like a huge vacuum.
Also if the outflow is positioned correctly there will be a circular movement in the horizontal plane of the entire surface. If the entire surface is not moving you know the flow pattern is not the best (despite high flow rate).

7. Here's a picture of how to place the intake and outtake so you get that "special" circular flow pattern (both vertically along the front glass AND horizontally so the entire surface is moving). Keep in mind that even pretty low flow rates will become very efficient IF you establish the flow pattern like that. DO NOT add any pumps/powerheads to that flow that shoot against it or perpendicular to it. They will act as blockage. Simply put your waste will not know which way to flow. It will stay floating in the tank forever and cause algae.










8. Remember that it is VERY important to always have some movement of the surface. Fortunatelly that is easily done by adjusting the outflow. Keep it close to the surface AND close to the front glass.

9. Note that the outflow and inflow are on the same side of the tank. As mentioned in (2) the intake must be a few inches above the substrate.

10. The proper water flow pattern can be achieved with any outflow (Lily pipe, regular pipe, HOB filter). But the flow pattern depends on the positioning of the outflow pipe. The pipe needs to be at a certain depth under the surface of the water. Too deep and there will be no surface movement. Too high and the water will actually shoot at an angle toward the bottom which leads to the circular movement not engaging the entire tank.
From all outflow designs the Lily pipe provides the most flexibility:
- It can be moved up and down easily (unlike HOB filters) 
- It has a wide "mouth" which will allows it to keep the flow pattern good even if the water evaporates 3/4" (unlike a straight pipe "mouth" which forces you to reposition it every 1-2 days.)
- The wide "mouth" engages water from the sides of the main stream shooting out of the Lily pipe better than just using a straight pipe. So with the same flow rate the Lily pipe moves the water better.

That's all. It is the single best way to establish flow pattern that is extremely efficient. No need for additional pumps. What you are really trying to do is to establish something known as "gyre". It has very beneficial results. Pictured below is the basic idea. The water ABOVE the corals flows in one direction. The water UNDER the corals flows in the opposite direction. That is what you are trying to do in a planted tank too. No additional pumps, no corals, no chaotic movement:








If the image does not open click on the link:
http://www.advancedaquarist.com/2007/1/aafeature_album/figure2.jpg


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## niko (Jan 28, 2004)

Some more on the Lily pipe functions:

Aeration:
The Lily pipe can be used for aeration of the planted tank at night. That is needed because the biofilter does not function very well at low pH. But in a planted tank plants benefit from injecting CO2. The reasonable compromise between supplying the plants with CO2 and being careful with the biofilter is to alternate periods of higher CO2 (but not way high) with periods of higher Oxygen. That's simple: Turn off the CO2 at night while aerating at the same time helps the tank in 2 ways:
- it increases the pH so the biofilter functions better and the suppressed organisms in it do not die 
- it supplies Oxygen which the plants need during the night









Surface skimming/cleaning:
The Lily pipe can create a gentle vortex if needed by careful repositioning of the pipe up or down. It basically sucks the surface of the water. The debries, film, or food get incorporated in the water column and end up in the filter.


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## Yo-han (Oct 15, 2010)

Agreed with all! Small rectification: oxygenation increases the pH so the biofilter performs better, not lowers... 

A little off topic maybe but Amano places the diffusor always halfway on the opposite side, as shown in the picture. I know this is so the bubbles get pushed down and dissolve better. But why halfway and not lower? Anyone knows this? I always place them as low as possible.


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## jeff5614 (Feb 15, 2006)

Yo-han said:


> Agreed with all! Small rectification: oxygenation increases the pH so the biofilter performs better, not lowers...
> 
> A little off topic maybe but Amano places the diffusor always halfway on the opposite side, as shown in the picture. I know this is so the bubbles get pushed down and dissolve better. But why halfway and not lower? Anyone knows this? I always place them as low as possible.


I thinks it's basically for aesthetics. It seems I've read a statement somewhere by ADA that CO2 diffusion is the same with the pollen glass half way down as when it's placed closer to the bottom.


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## niko (Jan 28, 2004)

I too think it is about some kind of pleasing impression. It also could be that the water flow hits the diffuser best when the diffusor is right in the middle of the water stream headed down. One strange thing that I have found was that it really doesn't matter if the CO2 diffusor is 1" below the surface of 10" below. I do not understand why but that is what I have seen.

About the CO2 diffusor placement:
Not everybody knows but there is a slight flocculation effect from the smooth stream of water flowing down meeting the CO2 bubbles trying to float up. Basically tiny waste particles aggregate on the surface of the CO2 bubbles and tend to stick to each other forming a larger particle. That larger particle is good for the waste removal because:

- it settles easier
- it can be trapped easier
- has much less surface area than all the small particles that formed it taken separately

That flocculation effect in a freshwater tank may not sound like something that important (as it is in reef tanks (skimming)). Different factors affect it and it may or not be visible. But from what I have seen when things are just right the effect is pronounced enough so you see a difference (clearer water) just by turning on the CO2. And you see a difference (water not so clear) when the CO2 is off.


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## jeff5614 (Feb 15, 2006)

As a bit of an aside, Frank from ADG mentioned to me that the ADA folks at the ADA Gallery in Niigata move the diffuser from one end of the tank to the other every couple of weeks. He said the CO2 concentration is always higher on the side of the tank opposite the diffuser.


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## houseofcards (Feb 16, 2005)

jeff5614 said:


> As a bit of an aside, Frank from ADG mentioned to me that the ADA folks at the ADA Gallery in Niigata move the diffuser from one end of the tank to the other every couple of weeks. He said the CO2 concentration is always higher on the side of the tank opposite the diffuser.


That's interesting. Never hear that before. Wouldn't the co2 concentration be reset many times over a few weeks? Not sure how this would be beneficial. I do know that on larger setups it's usually beneficial to place the diffuser on the same side as the outflow this way you not limited by the capacity of the filter to reach and scatter the co2 bubbles. As mentioned you don't need a lot of flow if done correctly, but you still need a minimum of reach.


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## niko (Jan 28, 2004)

In ADA's larger tanks there is sometimes a different flow pattern. I believe that there are two outflows and they shoot under an angle from the left and from the right. Each one shoots toward the middle of the bottom, closer to the front glass. I think Jeff was telling me about that. 

It'd be good if someone clarifies that, I'd like to hear more about it because good flow pattern in a big tank full of plants seems to be more of a problem compared to smaller tanks. Big size open space tanks (iwagumis for example) seem to not have an issue establishing the circular flow as described above.


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## jeff5614 (Feb 15, 2006)

houseofcards said:


> That's interesting. Never hear that before. Wouldn't the co2 concentration be reset many times over a few weeks? Not sure how this would be beneficial. I do know that on larger setups it's usually beneficial to place the diffuser on the same side as the outflow this way you not limited by the capacity of the filter to reach and scatter the co2 bubbles. As mentioned you don't need a lot of flow if done correctly, but you still need a minimum of reach.


It does seem that it would be reset, but I didn't think to ask much more. He makes some mention of it in his 80 page thread in TPT's nano forum also and I think has a bit of a diagram to explain it.


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## jeff5614 (Feb 15, 2006)

niko said:


> In ADA's larger tanks there is sometimes a different flow pattern. I believe that there are two outflows and they shoot under an angle from the left and from the right. Each one shoots toward the middle of the bottom, closer to the front glass. I think Jeff was telling me about that.
> 
> It'd be good if someone clarifies that, I'd like to hear more about it because good flow pattern in a big tank full of plants seems to be more of a problem compared to smaller tanks. Big size open space tanks (iwagumis for example) seem to not have an issue establishing the circular flow as described above.


In some of their larger tanks you'll see two sets of pipes. One set will be, for example, moving water from left to right along the front glass and the other set up to move water from right to left along the back glass. So it seems it would still provide the same flow as in your pic that you get with one filter in a smaller tank. Maybe the use of two filters on a larger tank was due to not having a larger filter on hand so they just went with two smaller filters or possibly they use two filters on larger more densely planted tanks.


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## niko (Jan 28, 2004)

Here's a real life example of how to *not* setup the water flow:

As we all know the internet is just about the most unreliable source of information you can find. And we love it that way. I can post about proper water flow all year long but I don't necessarily run my tanks that way. I admit it but I have no doubt that most people run utterly perfect tanks and whatever their flow is it "works very well". And all the other things they do work even better.

So here it is: Tank of a friend of mine. Over the years I've added filters, pumps, whatever, to make the super densely planted tank have some reasonable flow pattern. I cannot hang the filter pipes from the side of the tank. They hang on the back shooting toward the front glass. Pointing the outflow along the back glass does not work (plants too dense). The last "best" setup is using 2 pumps to make stagnant areas move. Smart move. Many people add pumps for the same reason, plumb special pipes, add jets, spraybars, increase flow rate, and sprinle kryptonite too.

Well, since the other day I have to feed the fish in that tank. I get to see the food floating in the tank and judge my own amazing flow pattern and my own genius.

Both are indeed amazing! Any food particle sinks for 5-6 inches and then shoots straight up! Then it is being carried sideways toward the left glass where it calmly settles among some dense crypt bushes. Fish can't get to it. Did I mention we are talking beefheart here?... Organics? What organics?

Moral of the story: Check your flow pattern using some slow sinking fish food.

No need to hear your observations. There is no doubt everybody's flow is perfect. So shut off your electric computer, get a non-electric chair, sit down, and think about something a bit. Anything.

I did just that the other day and lo and behold I quickly found a way to bend acrylic pipe without any kinks in any crazy shape I could think of. I will be adding flow along the front glass of that damn tank. Just like the picture in the first post of this thread shows. Being smart adding pumps is one thing, good flow is something else.


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## niko (Jan 28, 2004)

I think that most planted tank heads don't remember the old days of aquariums because they where not in the hobby back then. As many other things in life - old things have been packaged and marketed as new and not everybody realizes that. One example is the circular flow in a planted tank. For many people Amano is the one that invented this "fancy" flow that is shown on the picture in the beginning of this thread. Truth is pretty much everything we do today was used by German and Dutch aquarists. Here's a video from 1999 showing circular flow. At 5:50 they even show how the surface of the water needs to move:


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## Zapins (Jul 28, 2004)

Interesting video. I tend to agree with you on this point. It seems people like to rebrand old ideas. I mean just look at the soil idea. People swore off it for about 8 years there and all flocked to EI and PPS-Pro, and now everyone is interested in soil based "NPTs" and high tech soil tanks.


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## niko (Jan 28, 2004)

Using soil... Michael told me that very much every new person that comes to the club meetings asks about using soil, not EI or PPS. I was surprised. And just last night I accidentally found a YouTube video showing how to "dirty up" your tank. But what was interesting was that on the side there were all kinds of videos showing how to use "dirt" for a planted tank. Seems like there are hundreds of them on YouTube - some more detailed than others.

I am glad to see that trend. To me this is about common sense, not about what this or that person says is "the best" to do. Truth is there is no "best" anyway but just look how all of us fall for what not advice, including our own convictions.

There is another interesting video from Tunze - it shows how their pumps make more flow and less turbulence. The video is boring but I think it brings up an important point - a pump with certain flow (gph, gallons per hour) does not necessarily move the water as you think it does. If indeed getting as close to laminar flow as possible is the most reasonable way to setup the water circulation then one needs to discern between gph and actual smooth flow and be aware of that factor too.

An observation about "smooth" flow: On my big tank I have two Eheim Compact pumps. They discharge the water into the tank through two separate hoses with the same ID. One of the pumps is lower gph. The discharge from that pump is really smooth. The more powerful pump certainly makes a lot more turbulence. My point is that the flow rate and the ID of the hose have an impact on the turbulence. A dirt particle has more chances to linger in the tank if the flow is chaotic.


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## Michael (Jul 20, 2010)

An irony about the interest in soil substrates goes back to my childhood in the 60s. I ALWAYS wanted a lush planted tank after I saw photos of Dutch aquaria in my library's copy of _Exotic Aquarium Fishes_ (William T. Innes). The text noted that these tanks used soil substrates, but did not give details and said that this should "only be attempted by the advanced hobbyist". Of course, I was NOT an advanced hobbyist, so I never tried to do it.

But now I think that soil substrates (with moderate lighting, good flow, and high biofiltration) are the easiest way for beginners to have success with planted tanks.


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## Yo-han (Oct 15, 2010)

niko said:


> There is another interesting video from Tunze - it shows how their pumps make more flow and less turbulence. The video is boring but I think it brings up an important point - a pump with certain flow (gph, gallons per hour) does not necessarily move the water as you think it does. If indeed getting as close to laminar flow as possible is the most reasonable way to setup the water circulation then one needs to discern between gph and actual smooth flow and be aware of that factor too.
> 
> An observation about "smooth" flow: On my big tank I have two Eheim Compact pumps. They discharge the water into the tank through two separate hoses with the same ID. One of the pumps is lower gph. The discharge from that pump is really smooth. The more powerful pump certainly makes a lot more turbulence. My point is that the flow rate and the ID of the hose have an impact on the turbulence. A dirt particle has more chances to linger in the tank if the flow is chaotic.


I think you love this Niko: http://www.advancedaquarist.com/2011/7/aafeature


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## Phil Edwards (Jan 22, 2004)

Folks,

When discussion laminar and turbulent flow, PLEASE PLEASE PLEASE, remember that Laminar doesn't mean Unidirectional. Laminar flow is what Niko's describing as "gentle" aka not chaotic. 

Thanks.


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## Emily6 (Feb 14, 2006)

Ok, I have a question about layout- if I understand correctly, the outflow should be opposite the intake, both on the ends of the tank (lengthwise). I have a canopy on my tank- so the hoses only fit across the back. So right now, I have the intake in one corner and the outflow in the other, aimed diagonally towards the front. My diffuser is under the outflow, theory being that it would give the most travel time for the CO2 bubbles (but I see others place it near the intake instead). I have a powerhead at the surface, above the outflow, aimed straight across and slightly upward (I know things need work here).

Do most tanks have the hoses visible along the sides of the tank or is there a way around this that I'm missing? I think a lot of swanky tanks are photographed with the equipment removed so I don't have a lot of real-life examples to review.


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## niko (Jan 28, 2004)

Yes, what you see on photographs is usually far from what you will see if you walked in to look at the tank. People use all kinds of ugly equipment. The Japanese are the kings of ugly outside of the tank. Think wires, home made reflectors hung with pieces of wire, ugly sponges inside the tank etc.

With a canopy you can't do much unless you add internal pumps. The basic idea is to have the flow move in something like a circle. So do not put pumps shooting against or across each other. Somehow make yourself understand that with careful adjustment of the direction of the flow you can make the entire volume of water in the tank move very strongly. With just the right direction of the flow you may actually have to remove pumps out of the tank! I made all the water in a densely planted 4' long tank move perfectly by using a tiny weak internal pump (it shoots water along the back glass and close to the surface). That tank is described in post #11 above. The tank has a tall ugly canopy and I cannot put any hoses/outflows on the side. After adjusting the flow pattern the tank breaths a new life. Including using 10% of the ferts I was using before. It's amazing to me what profound change the tank has undergone since post #11 in September.

All of the above talk about water flow is counterintuitive and that's why I say "make yourself understand" that careful adjustments make the good flow or break the good flow. But the adjustments are truly fine - in my 6' long tank for example all of the waters stops moving if the 1200 gph outflow moves 1/2" to the side. Having the outflow close to the front glass seems to help a great deal. In the case of the 4' tank I mentioned above the flow is along the back glass. All of that has to do with the physics of water movement which don't make much sense to us, regular, folk. Experiment with what you have. A simple rule is - make the leaves of all plants gently sway in the current. How you do it doesn't really matter but if they wave in the current you have vastly improved your planted aquarium's conditions.


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