Water flow better as a vortex vs random flow

[a1amap]

Remember when you were little and would try to walk around the above ground pool really fast to create a whirlpool? How about the sink drain?
I had a conversation with kaptken who had attended the NJ frag swap and talked to someone about the problems with "random flow" tanks vs. creating a vortex. As I thought about the idea it really makes sense. Hitting the opposing turbulent water and then losing power wastes most of the power of the random flow. I also remember trying to stop after the whirlpool in the pool got started and it would drag me around. If the rock in you tank had an open structure and was not piled up against the rear glass this should work. The pump would not have to work very hard once the water got moving.

This would bring food to the corals and remove wastes. The pump would not have to be huge because the water will continue to swirl around the tank. I remember the debris in the pool use to collect in one spot. This would make it easy to remove the waste if any. Is anyone running a tank like this? What would be the downfalls of this?

 

[WarrenG]

I read the articles at advanced aquarist.com about flow. One of the articles talks about setting up a tank to create a whirlpool.

I have one mj mod in the back of the tank pointing to the left and another one pointing to the right. They are on in alternating cycles of about 8 minutes (Chauvet4005 timer). This allows time for the water to get moving in one direction so the flow is good.

The rocks and corals create some turbulence anyway, just as they do in the wild.

IME, in the wild, most of our corals see mostly flow from currents that go for hours in each direction, not surge.

I have a RedSea Wavemaker for sale.

 

[garygb]

Not to get off topic, but how well do the mj mods work, and where do you get them?

 

[WarrenG]

I've tried two different versions of the mods. One was junk. The one I've tried that works well is the "Algae Free Sure-Flow. They work so well that I'm using them on MJ600's even though I own some 900's and 1200's. They're widely available and I got mine at Marine Depot.

 

[garygb]

Appreciate the response Warren, I will check them out at Marine Depot--and start a whirlpool of my own perhaps.

 

[ahullsb]

I would like to here more people weigh in on the whirlpool effect. I was always told it was bad, but now that I think about it more, I don't see why...

 

[WarrenG]

IME, you don't really end up with a whirlpool effect because the water is bouncing off of rocks, glass, corals, etc. I do have two un-modded mj's mounted on the back glass pointed right at the front glass and this breaks things up occasionally. When I watch the bubbles and stuff in the water moving around corals in all the different parts of the tank the flow looks good.

 

[Mattmcf]

Could you really create the whirlpool effect without having a cylindrical tank? remember those above ground pools are perfect circles. seems that the 90 degree corners would put a stop to the flow. Reminds me of a "lazy river" in a water park... they are always shaped with rounded corners, i have never seen one with a "real corner". I bet this is a great idea though with those cylinder tanks.

 

[WarrenG]

The idea is not to create a perfect whirlpool, but by using all the water pushers at the same time in one direction around the perimeter of the tank you can get excellent flow through all of the tank.

For example, I have a mj-mod on a mj 600 and it goes about 12 inches to a 45 degree corner, then another 18 inches to a 90 degree corner, and then is still able to move an anenome that is another 35 inches away. So, that's one and half corners and more than 5 feet.

 

[tylorarm]

I've tried to do this in my 480gl tank, not sure how successful. I have flow of 84" x 48" x 28" tank directed in two semi circles around two islands. Idea is water is pushed equally from both rear corners horizontally on back side, then pushes through the central canyon, hits front glass then parts each way around islands, gets pushed from closed loop outlets in islands that add velocity to flow, then when flow gets back to overflow corners is sucked by intakes of closed loop and overflow which are stacked vertically perpendicular to outlets. Works well now but just getting started so don't have much coral interferance.

 

[tylorarm]

Just to clarify, my post should read two circles not semi cycles. Hopefully that makes more sense now...

 

[a1amap]

There would be loss in the corners but not enough to stop the flow. Have you every had a power head facing the glass? The water will bounce off and hit the sand. There will be some loss of power but not as much as 2 opposing forces colliding. when I cleaned out my sump which is 40 gallons I used my arm to create a whirlpool, it kept going for some time after I stopped applying the motion(my arm).

I am wondering if it would work better having the returns spaced down the back vertically or just have them spread around the tank aiming the same direction to keep the speed of the flow up.

 

[WarrenG]

I think it was one of the flow articles at advanced aquarist that talked about a "gyre"(?). He put the pumps in the back of the tank stacked vertically, behind a partition to hide them and to help control the flows.

 

[sjm817]

My 36", 30G fuge has 2 MJ900s without mods. One points rear left, one points front right. The body of water does spin and keeps the ball of chaeto spinning as well. On my old 90G tank, I did the same with a pair of Mj1200s and it also worked. I now run a 180G with a pair of Tunze 6100s running in a traditional fashion. I do wonder if setting up a whirlpool would be worth while. I dont think the stream type pumps with the wide flow pattern would be the way to go. The type of pump with a narrow directed output seems to be better for this application. The only thing is, reversing the direction is not really possible unless you move plumbing/pumps around.

 

[IPT]

In theory, a unidirectional flow would not be ideal. I believe corals are stimulated and growth patterns are affected by the direction and forces of flow. In all lilkelyhood with constant flow in one direction you'd get some unnatural growth patterns (maybe all leaning into or away from the current?). If you did this I would thik you would have to at least have it alterante direction a few times a day (like the tides) to keep growth patterns natural.

 

[WarrenG]

The two pumps are on timers and point in opposite directions.

 

[tylorarm]

I had planned to use my vortecs to create more variation in the laminar flow, however, when you see food and stuff flying around the tank the flow is much more variable than I'd have expected. The worst part of my design is that the front side of my islands are in the backflow of an eddie, but I plan to keep some lower flow corals there and it's still a fair bit of flow. In total i have two returns from hammerhead with eductors, two darts, two vortecs, and one RD 2100glph all directional consistent with two circles.

 

[liveforphysics]

Keep in mind a couple of things. Laminar flow stores and best conserves kenetic energy in the flow. This is why a small pump placed correctly can cause a whirlpool of flow after a few minutes of constructive flow acceleration.

Next, what happens when that laminar flow touches a coral? It instantly becomes turbulent upon aproach of the boundry layer of the coral, and then maintains wild turbulent swirling flow through the branches of the coral and out. A few inches after leaving the coral it begins to settle back into a laminar mode and continues along until it hits the next coral.

To put is simply, getting a whirlpool going is a excellent thing, and it's been proven many times to grow as well or better than alternating or constantly chaotic flow. The key difference is that it can develop insane amounts of water motion in the tank with very little energy used.

 

[WarrenG]

Yes, a closed loop pushing 1000gph with outputs all fighting each other, or 2 mj mods working efficiently?

 

[mxett]

I used to do a similar 'whirlpool' flow effect in my 90g by using two tunze's in opposing corners that would push all the water in a clockwise direction. Then 12 hours later I would change their direction so the pushed the flow in a counter-clockwise direction. Worked really well. What helped was having the rocks in the midle of the tank, not up against a wall.