# Circular flow?



## niko (Jan 28, 2004)

What is the purpose of this contraption? My guess is to allow for water flow rate that is too big for a small tank and if released from a pipe outflow would peg plants and fish to the opposite glass.

Any ventury tricks going on? Any special water movement with that glass ring?


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## Yo-han (Oct 15, 2010)

Your on fire today, aren't you Niko 

This one is indeed to reduce flow and to look fancy probably. I wondered about another benifit compared to the lily pipe but couldn't find one. Perhaps someone else can find one.


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## Tugg (Jul 28, 2013)

I can only speculate that it takes the 1/2" tubing and brings it to a 2" opening, giving a soft high volume flow.


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## Phil Edwards (Jan 22, 2004)

That's really interesting. Looks like it's intended to move a lot of water gently; particularly in a small tank. I'll have to think about the fluid dynamics and all that.  Thanks Niko, as if I didn't have enough to do already. :icon_hang


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## niko (Jan 28, 2004)

Honestly as soon as I saw this glass circle I thought "Aha, it is meant to reduce the impact of the water flow but also it maybe creating something like a vortex sideways engaging the water from the side." Kind of like a very wide suction.

I know I am overanalyzing this but who knows - after the simplicity and multi-functionality of the Lily pipe I am suspicious of anything Japanese.


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## Phil Edwards (Jan 22, 2004)

It looked to me like it pushes water out both sides to create a diffuse flow that'll move water along both the front and back of the tank without blowing things sideways or pushing fish against the glass.


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## niko (Jan 28, 2004)

But the way I see it the water coming out of the "ring" will not be one solid "shape" - like a cylinder going to the right and to the left. It'd be nice to see what a few drops of dye reveal about how the water moves.


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## Yo-han (Oct 15, 2010)

niko said:


> But the way I see it the water coming out of the "ring" will not be one solid "shape" - like a cylinder going to the right and to the left. It'd be nice to see what a few drops of dye reveal about how the water moves.


I finally managed to convince my boss to be the first lfs that deals in ADA stuff in the Netherlands. He couldn't see people spending that much money on stuff. But after selling two pincets for €60,- each (over $80,-) in a month (compared to our regular pincets for $10,-) he was convinced for sure! Maybe I can add one of these to the order list next time and try it out. Will take a few weeks though!


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## Phil Edwards (Jan 22, 2004)

Whelp, I just set up a tank last night to do a little experimentation. It's 48" long x 24" wide x 12" high (60gal) with an Eheim 2026 Pro II filter currently arranged without the spraybar with the outlet close to the front glass. The CO2 diffusor's on the side wall opposite the filter outlet and there's enough current to keep 98% of the bubbles from reaching the surface. We'll see how the plants grow with the gyre movement for a while then switch to the spraybar and see how things do after that.

So far I've noticed good circular flow around the perimeter of the tank and a strong undertow/counterflow going back toward the outlet until about the middle of the tank where it gets disturbed by an eddy created by a standpipe. I'll get pics once it's cleared up enough.


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## niko (Jan 28, 2004)

For what it's worth here's an experience with placing a spraybar on the bottom of the tank: I made a spraybar that spanned the entire length of a 4' long tank. I placed it on the bottom glass and stuck to the back glass. It shot the water along the bottom.

I guess you can make a very unique tank using that arrangement - the few Java Fern plants that I had floating in the tank started to oscillate suspended in the middle of the water. As if they were spinning around an invisible string stretched from the left to the right glass. If plants can grow on a continuously spinning substrate you can have a tank that is completely baren and the plants (mosses maybe) grow all over cylinder that constantly spins in the middle of the tank. Imagine the wood in the picture below constantly spinning along the long axis. Not very pretty idea but unique for sure:









As soon as I planted a few more plants on the bottom of that tank the eerie endless spinning could not be sustained. I guess the dynamics changed completely by adding just a few obstacles. The moral of that maybe that the outflow must be placed to shoot along the most unobstructed part of the tank - usually the front glass. But I now have a tank which has a pump shooting water along the mainly unobstructed back glass. The water moves very well in that tank. It does look like there is a rule to making the gyre work - "shoot the water along the longest open space in your tank and you will involve most of the water in the movement with the minimal flow rate possible".


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## Phil Edwards (Jan 22, 2004)

niko said:


> But I now have a tank which has a pump shooting water along the mainly unobstructed back glass. The water moves very well in that tank. It does look like there is a rule to making the gyre work - "shoot the water along the longest open space in your tank and you will involve most of the water in the movement with the minimal flow rate possible".


That's absolutely true and holds to what the author of one of those previous articles discussed with talking about fetch. The farther the initial stream can move before hitting an obstruction, the more effectively inertia and the viscous forces will keep the whole mass of water moving.


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