Flow in a hexagon tank?

[Absinthe]

Let me throw an idea out there...

I have been analyzing (in my mind at least) flow patterns in a hexagon tank.

Tank is 60 gallons, 27" x 24" x 28" high

Height will obviously be the issue to overcome here.

Lets assume a FOWLR tank...20-30x turnover, so maybe a minimum of 1500gph

Proposed design top down

Proposed design front

Same tank with single large pump/powerhead

2 other designs

Anyone have any thoughts on this setup?

Hoping to do a 60g Hex FOWLR (not a lot of LR).


ALSO...would having the same size tank, but a CUBE make things easier as far as water flow? 24" x 24" x 24"?? Perhaps easier with aquascaping, but again, not planning on a whole lot of rock anyway

Thanks

 

[kathainbowen]

Hooray, a post I can actually feel like a total expert on!

I actually moved everything out of my pico finally and comfortably into my 10 hex, and things are going great. But, definitely, with the height and with how easy it can be to end up with an absolutely jammed tank, hexes can be dead patches for current.

To compensate, I'm actually running something similar to what you are describing of using two powerheads on each corner to add to the flow. However, one of the powerhead (my left one) is actually about three inches below the surface and slightly angled down, where my right powerhead is only about 6 inches above the sand bed. This has allowed me to have the flow I'd like while keeping the powerheads from constantly tossing up my sand bed and bothing my nassarius snails. My powerheads' angles are also determined by the rock around it (one powerhead if positioned to flow with the side of the tank (*the top one, creating a counter-clockwise and slightly downward flow). The other points somewhat along the tank, but also slightly into the rock pile to split it up a bit (creating a slightly clockwise flow) It's working very nicely for me, but I also am working with a tall rock stack (*one piece actually pierces the water).

Now, in your tank I cannot make any assumptions that it will work just as well for your tank. With a short rock pile, and two powerheads creating a good stiff current, there may not be enough to diffuse the current, and you could end up with too much flow depending on what kind of fish you plan to keep. I know you said you want a FOWLR, but what kind of fish are you planning to have? This will help determine if the current will be too much, or just right.

 

[Absinthe]

Good point about the rock deflecting some of the current.

Havent really decided on fish at this point, but nothing that couldnt handle nice brisk flow.

I am thinking that with the powerheads in the back corners and the front glass only 24" away, the flow would bounce off the irregular walls pretty nicely and give an irregular flow.

Plus the 300gph or so from the skimmer would keep the surface agitated.

I am thinking of having the powerheads a few inches down, one angled towards the front bottom corner, the other almost straight across the tank to the opposite front corner.

I was considering Hydor Koralia 3's @ 850gph each (25x turnover) or 4s @ 1200gph each (40x turnover, but a gentle flow)

 

[Carlo]

I've never ran a hex tank so I'm only asking a question.

If you have say 2 powerheads would you want to have them pointing at each other to create a current that crashes into each other or would you want to point them say clockwise to create a flow the circulates the tank making it easier for the fish to swim?

Sorry to jump in with a stupid question like this but I never thought about the current in a hex before until reading this.

Carlo

 

[Absinthe]

I've never ran a hex tank so I'm only asking a question.

If you have say 2 powerheads would you want to have them pointing at each other to create a current that crashes into each other or would you want to point them say clockwise to create a flow the circulates the tank making it easier for the fish to swim?

Sorry to jump in with a stupid question like this but I never thought about the current in a hex before until reading this.

Carlo

Same question I have been asking to myself.

Anyone with experience with that?

I would say for a REEF you would want the random, turbulent flow.

For FOWLR perhaps the directional water movement.

But even with a hexagon, the irregular shape should lend itself so SOME random flow, right?

 

[kathainbowen]

I've never ran a hex tank so I'm only asking a question.

If you have say 2 powerheads would you want to have them pointing at each other to create a current that crashes into each other or would you want to point them say clockwise to create a flow the circulates the tank making it easier for the fish to swim?

Sorry to jump in with a stupid question like this but I never thought about the current in a hex before until reading this.

Carlo

It's not really a stupid question, so don't feel bad. In fact, I actually positioned the powerheads based off of the rock, and, then, adjusted everything for both the fish and coral until I was happy with it. But, a large part of how I adjusted the powerheads and the flow related to the fish, and ended up inadvertently working in favor for coral growth, guiding the coral a bit in the directions I want. It's rather like using flow to create bonsai. Such as, I have a huge pile of Xenia elongata (*thanks Ed!) that started as a tiny frag, positioned under the return for my Aquaclear, pointing all of the polyps towards the front of the tank and encouraging the growth away from some rics.

To be honest with you, It really depends on how powerful of powerheads you have and how they are angled working together, in addition to the structure of the tank, as per exactly what interaction you will want with the powerheads and the rock. A good way to obverse this is to make a mix of powdered calcium or add a liquid calcium. Most calcium supplements give a good white cloud, so you can really observe your flow before adding fish and/or corals. Your flow is going to vary depending greatly on a bunch of different factors INCLUDING powerhead placement and liverock, all workin together.

In this example, with two strong powerheads pointing towards the front/bottom of a tank and angled almost towards the same spot, there could be a strong, turbulant reaction point. That's also because there isn't going to be a lot of schtuff to diffuse the current around. In a reef, yes, a strong turbulant, and varying current is present. However, the current is still going to interact in the same way, still creating a laminal flow. It's just going to be a laminal flow going in all directions!

 

[Absinthe]

This is turning out to be a great discussion!

I have decided to try both powerheads in the back "corner" of the tank, each facing forward and slightly across the tank in the opposite direction.

One (1200gph Koralia 4) will be almost horizontal and the other (850gph Koralia 3) will face slightly downward. Both of these pumps will be on the wavemaker made for the Seio pumps which offers a soft start and increase to full power mavemaking function.

I am hoping that the Korali 3 @ 850gph foacing slightly downward is enough to move water but NOT so much as to create a sandstorm.

The total powerhead movement in the tank will be 2050gph with another 295 coming from the maxijett on the skimmer.

Anyone have any thoughts on that? Too much flow? Too little?

I have decided that the tank will be a FOWLR/softie reef. Xenia, anthelia and maybe some shrooms. No more corals for me at this point...too much $ and too much babysitting!

Plus, I am considering some non reef safe fish.