Water flow

[JimDandy]

My apologies if this question has cropped up before but I just cannot find a good answer to the question “How much water flow”?

I suspect the answer will likely begin with “It depends”, but I’d like to ask in general terms. For instance, I’ve seen quotes such as 15-20 times the tank size, so a 100 gallon tank might need 1,500 to 2,000 gph flow using powerheads or other pump sources. I’ve heard that this number needs to take into account the number of gallons being returned, per hour, by your main system pump, and I’ve heard from other sources that you don’t count the main system pump volume…which is it?

Maybe I’m trying to be too simplistic, but as an example, I’d like to know if this is an acceptable model to determine the number of powerheads to use. Tank size (X) times some value of multiplier (Y). Subtract from that the flow of the system pump (S) (or not) then divide that by the flow of my chosen powerhead (Z) = number of powerheads (rounded up to nearest whole number).

Tank size = X
Multiplier = Y
PH flow rate = Z
System Pump = S

X times Y divided by Z or ((X times Y) minus S) divided by Z = # of powerheads

Maybe the multiplier differs if you are doing a FOWLR or plan on having an SPS or LPS tank but I’m trying to get in the ballpark and there are so many widely differing opinions.

In addition to a mathematical approach, I’ve read in some journals that you can measure flow rates by timing how long it takes a piece of food to travel a certain distance across your tank. I could not see how to turn that into a number of powerheads since poowerheads are not rated in flow rates.

 

[Brenden]

What type tank has everything to do with it. FO, LPS, SPS etc. You can get by with 10x flow with a FO tank. 15-20x is generally OK for a LPS tank. I would up it more if going SPS. IMO the more the better. My newest tank has around 70x flow rate. You can count the return flow as long as you direct it with locline etc so it can be used. Generally speaking I would not bother though. If you go with the bare min you will wish later you had more flow.
Tell us the type tank you are planning and the size.

 

[returnofsid]

Keep in mind that, just as important as amount of flow, is quality of flow. Lots of GPH of linear flow isn't very good, while even a lower GPH of good random flow is excellent. The best is higher GPH and still random. I'd recommend 10-15X for soft corals. 15-20 for LPS and LOTS for SPS...lol. As with any "rule of thumb" there are always exceptions. For instance, Bubble Coral, Torch Coral, Frogspawn, Hammer Coral...these are all LPS but don't like lots of flow. I have them in my tank but they are in areas that are somewhat protected from high flow by rock work.

As far as X(Y)/s*z....I rocked at Algebra in 8th and 9th grade but that's been a LONG time ago. If you have a mathematical mind, analyze things, put together a formula and post it for us all....lol. Maybe you'll come up with a new and improved method!!! Then you'll have to re-teach Algebra to us though!!! You've been warned...lol.

 

[Krish]

See if this thread gives you any ideas.

http://www.reeffrontiers.com/forums/showthread.php?t=18140

 

[reeftnk101]

Flow In An Sps Tank Is More Important Than Lighting. The Corals Depend On The Flow For Food,oxygen,removal Of Toxins On There Membranes Etc...