# Video: Has to do with Laminar flow



## niko (Jan 28, 2004)

Some time ago we all agreed that in a planted tank it's better to have laminar flow. Compared to turbulent flow it should provide better removal of the particles that we want to go through the filter.

We talked about ADA's way of setting up the outflow and inflow. How they make a gyre - a directed stream of water that "pulls" particles from all parts of the tank.

We all agreed that perfect laminar flow is impossible to create in a planted tank. But one needs to strive to be as close as possible.

Well, this video will give you a very good visual idea how the water in the aquarium can be seen as a single body. That's the basic idea behind using a gyre and the efforts to maintain laminar flow. Simply put if we can grab and pull the water in one corner of the tank we can move the entire volume of water. And make it go through the filter. And all the particles, from all corners of the tank too of course...

Hope that makes sense. And hope that the people that were interested in that discussion still remember it. Here, this is how the water can be seen behaving as a whole body. The effect is created by using a special pump set to work in a special mode. Simply put it's like pushing a swing - a small push in the right moment and place makes the entire swing go back and forth further and further and further. Meaning that if you pull gently at one "end" of the water and keep doing it you will involve the entire body of water and if the debries from around the entire tank are in suspension they will come along too:


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## JustLikeAPill (Oct 9, 2006)

*Re: Video: Has to to with Laminar flow*

Very cool! If you remember my results posted in the old thread ( I even made a little diagram/drawing) is is what I experienced when I moved my filter pipes to the front/back.

I didn't get the wave motion, but the direction of the water was the same. Due to the lily pipes shape it was swirling around in the motion you see above, but also pulling from the end of the tank opposite the outflow and dragging water to the inflow.

One day, I would love to get that pump system when I get a bigger tank.


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## Ernie Mccracken (May 15, 2011)

For the lurkers:



wiki said:


> Laminar flow, sometimes known as streamline flow, occurs when a fluid flows in parallel layers, with no disruption between the layers.[1] At low velocities the fluid tends to flow without lateral mixing, and adjacent layers slide past one another like playing cards. There are no cross currents perpendicular to the direction of flow, nor eddies or swirls of fluids.[2] In laminar flow the motion of the particles of fluid is very orderly with all particles moving in straight lines parallel to the pipe walls.[3] In fluid dynamics, laminar flow is a flow regime characterized by high momentum diffusion and low momentum convection.
> 
> When a fluid is flowing through a closed channel such as a pipe or between two flat plates, either of two types of flow may occur depending on the velocity of the fluid: laminar flow or turbulent flow. Laminar flow is the opposite of turbulent flow which occurs at higher velocities where eddies or small packets of fluid particles form leading to lateral mixing.[2] In nonscientific terms laminar flow is "smooth", while turbulent flow is "rough."
> 
> ...











An object moving through a gas or liquid experiences a force in direction opposite to its motion. Terminal velocity is achieved when the drag force is equal in magnitude but opposite in direction to the force propelling the object. Shown is a sphere in Stokes flow, at very low Reynolds number.









In the case of a moving plate in a liquid, it is found that there is a layer or lamina which moves with the plate, and a layer which is essentially stationary if it is next to a stationary plate.









The streamlines associated with laminar flow resemble a deck of cards. This flow profile of a fluid in a pipe shows that the fluid acts in layers and slides over one another.


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## niko (Jan 28, 2004)

I can't think of anything to say but started typing.


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## fishyjoe24 (May 18, 2010)

interestng video a lot of the salty people are using those they can push out almost 3,000gph per an hour... what i also played around with is power heads. one power head on the left point up to carry water to the top right back corner which push water to a power head on the top front right corner then that one push water to the left power head...


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## Tex Gal (Nov 1, 2007)

So Niko I remember reading where John C. is using one of these pumps. I can't imagine how it would work in a planted tank. The one you sent a link didn't have movement like that. Am I mixing something up?


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## niko (Jan 28, 2004)

Oh no no! This wave action is not to show what we want in our tanks. It just shows how the water can be viewed as one whole body. All of it moving together. And you can use these properties of the water to achieve better filtration if you point the outflow in a certain way, place the inflow precisely and so on. That's all.

I personally consider these wavy tanks super ugly. Imagine having this sloshing abomination in your living room. Very beautiful indeed. I do understand that the animals probably love it because they are used to such wave action. But it just looks really bad to me.

--Nikolay


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## Tex Gal (Nov 1, 2007)

Yes I understand the example. Did John C not use these pumps?


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## niko (Jan 28, 2004)

I don't know if he used them. In his super sleek "Vanilla" tank there is one I believe. But I'd be something to hear that the pump is used in that wave mode.


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## mudboots (Jun 24, 2009)

I've been traveling a lot lately and was able to compare two "planted" systems recently, the Llano near Junction and the San Marcos. I am well convinced about the laminar flow, and I am eager to play with volume as well. Looking at both systems where the vegetation was super thick, obviously the laminar vs turbulent depending on the exact location and depth. But the water flow was amazing regardless, and the plants looked great. In the deeper areas of both vegetated streams the flow was like a wall of water moving over and through the plants, and I pondered how on earth I could replicate that kind of movement in an aquarium. I'm not sure it'd be feasible, but I could probably come close with a large enough tank, and a broad enough water outlet and inlet (but that means $$$).

I'm mostly just excited to see a filtration sub-forum and decided to ramble on a bit, but also, take a moment to picture our vegetated streams/rivers and what the water movement looks like. Maybe we should get a trip to the Llano scheduled. It's great fishing as well!


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## ObiQuiet (Oct 9, 2009)

mudboots said:


> ...the flow was like a wall of water moving over and through the plants, and I pondered how on earth I could replicate that kind of movement in an aquarium.


This reminded me of the Streambank Paludarium thread. The pictures seem to be gone, but it's a long and narrow tank, about 7:1.

I've also found myself coming back to the "Excited Word" thread every so often, and thinking about how one might construct a more standard shape tank where the entire right side is inflow, and the entire left side is outflow, like a windtunnel or hydrodynamic test tank. Maybe 1" thick acrylic with grids of horizontal holes as the left & right boundaries of the "display area".


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## mudboots (Jun 24, 2009)

You'd have to be willing to sacrifice some aquarium space, but it would theoretically work great. I am trying to figure out how to post videos on a thread I just moved over here. We'll see if I can figure it out, but if I can get it to work, the outlet on the filter is a 3/8" hose connected to a 3/8"ID outlet, and the inlet is a 1/2" pvc overflow. Just changing the discharge position had an instant effect on the water flow (top, typical to most HOB filters vs down at an angle against a corner to spread the outflow).


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## Chalcosoma (Sep 14, 2012)

Hi there, I will be attempting a kind of grid done anther way...will let you know how it goes.

Cheers


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## ObiQuiet (Oct 9, 2009)

niko said:


> Some time ago we all agreed that in a planted tank it's better to have laminar flow. [...] We all agreed that perfect laminar flow is impossible to create in a planted tank. But one needs to strive to be as close as possible.


In reading this http://www.janrigter.nl/mattenfilter/ it occurred to me that one way to strive for laminar flow would be two mattenfilters on opposite ends of the tank.

So, I cobbled together an image of what that would look like based on the pictures in the article:









Not as visually elegant as ADA's method, to be sure. One could hide the tank ends, though.


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## niko (Jan 28, 2004)

Two things:

1. That setup will require a pump with a very high flow rate to make the flow actually detectable.

2. Look at what is happening with the Oxygen here: 
The Mattenfilter on the left processes the water and reduces the O2. That water, with very little Oxygen, goes to the Mattenfilter on the right. It will all work out probably but filter #2 is always been kept suffocated. This is not about biofiltration you might say. But to that I'd say that what will be happening is having aerobic and anaerobic filtration depending on each other want it or not. Daisy chaining filtration is a bad idea and in this case MAY cause a big problem. 

Of course all of that is theoretical and the only way to see if this setup works is to try it with a large flow rate pump. Despite what I said above the idea to attempt to create laminar flow that way is good.

My latest idea is to hook up my canister filter hoses to U-shaped pipes that have a diameter larger than the hoses. Basically spreading the flow over a larger area. From the videos of "cannons" shooting water in a perfectly laminar manner we have seen that a laminar flow is very hard to achieve straight out of a pipe. So your idea is probably very good.


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## ObiQuiet (Oct 9, 2009)

Good thoughts, Niko. 

This is an interesting thought experiment. (Wish I had a tank I could use to try it right away)

1. The flow rate is probably governed by the porosity of the filters. Since it's not a closed canister, a larger pump can't force more flow through the filters. I bet the pump would have to be adjusted carefully to maximize the flow rate without exceeding what the filters can pass. And, it would change over time.

2. Good point about the O2 and daisy chained filters. I'd think adding a bubbler or venturi air intake to the pump output would work.

Another consideration is that one of your main points about laminar flow was about keeping mulm from accumulating by making sure it gets to the intake. The classic mattenfilter is too dense for that. I'm not sure that a foam exists that is dense enough to provide the directional flow while still allowing larger particles through. Perhaps the two filters would be made of different stuff...


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## niko (Jan 28, 2004)

I used Poret cubes (the foam for the Mattenfilter - the only foam on the market actually designed for fish keeping) when I ran the rare fish import business. What I saw is that the Poret accumulates a lot of extremely fine debries. Like mulm. If you stick your hand in the crystal clear tank and pull the Poret cube up it releases very much all the particles. They freely flow out of the filter. The pores are very large.

So the Poret foam does not clog. It is designed to not clog. If it does something is severely off with the release of organics in the tank. By the way I had a sick discus which someone gave me to keep until it dies. I put him in a 10 gallon tank. When it died I didn't remove him from the tank. It fell apart to a skeleton. But the Poret did not clog. My point is that the severe organic influx did not clog the Poret.


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## niko (Jan 28, 2004)

Here's another video. It basically shows how a nerdy techie can get way off with an idea that seems great. Yes, the sea creatures just can't do very well without feeling the lul of the waves. Can't deny that. But who would want such a wave motion in their living room? And to add a synchronised led "lightning" to that. That's too much.

But there is something interesting about this ugly wave motion. One of the viewers of the video pointed out that despite the uglyness of the wave that motion really helps keep detritus suspended and that way it can be sucked by the filter. THAT is the interesting point in this video:






So, once again, the kind of motion that we engage the aquarium water can actually help the removal of particles. Look at the wave on the video - it smacks you as a fluid, smooth underwater motion. Yet it keeps particles suspended. I thought that was another interesting point somehow connected with the laminar flow discussion.

And on the topic of making dirt suspended: In a planted tank one can dislodge debries constantly if there are quite a bit of Amano shrimp and Otos. Both of these animals with their incessant digging do raise up clumps of debries. Don't look at them as only eating waste - they could also help direct it toward the filter.


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## Michael (Jul 20, 2010)

Watching that tank for very long would induce motion sickness. But the suspension of particles in the water is really good.


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