How big of a pump do I need?

[tantricfish]

Ok... I promise I have tried to read through archives
I have a 90 gallon tank. After much thought, I have decided to go with a refugium filtering system.
I am shopping for pumps and I just read a post that said I want a pump that will move a minimum of 10x-15x the water volume in my tank, per hour? Is this TRUE? That just seems like a LOT of volume.
I appreciate any and all comments!!!

 

[stingrayman]

That`s right, 90 gallons needs a pump of at least 900 gallons an hour.
a little more is better. Just make sure you have enough drains to flow that much water.
I have a 220 tank and 55 gallon refugium, pump is 1200 gallons an hour with 4 one inch pipe drains.
On another tank I have a 55 gallon reef,29 gallon ref. pump is 780 gallons an hour with 2 one and a quarter inch drains.
hope this helps.

 

[fender]

I am probably walking to the beat of a different drummer here but I tend to disagree with the folks saying that your flow to and from the sump needs to be in the 10-20X turnover range.
Here's why:
1) I agree TOTAL turnover should be 20x or more but most people achieve this with powerheads and/or closed loop. True this means more "pumps" but the cost will be lower and you don't have a single point of failure. If you rely on your main pump for flow and the pumps fails... you will have a dead tank. With 1/2 to 3/4 of your total flow in power heads/close loop - you are still ok.
2) Why so much to the sump? Most Skimmers, especially the newer recirculating, work best at slower flow through rates. The longer the bubbles collect crud, the more crud they collect. Isn't true of all skimmers (beckett and downdraft flow a bunch) but for most it is true.
3) Refugiums don't need alot of flow through them either - depending on what you are growing in there some need very little flow.
4) Bigger pumps generate more heat, use more electricity, cost more, make more noise.
Having said that...if you want no powerheads, no closed loop and the return pump to supply all your circulation... then you need to get the big pump.
In short, determine what you will be doing below the tank and how much total flow you need in the tank. Figure out how many and what type of power heads you want to use and their flow. Subtract the difference and buy a pump slightly higher than that.
Example: I have a 65 gallon tank. My total desired flow is about 1500-1800GPH . I have a Mj900 modded flowing a conservative estimate of 1000GPH and an mj1200 flowing 295gph . My return is a mag 7 moving ~500GPH. Puts me right where I want to be.

 

[bacardi151]

IMHO,
Size your return pump appropriately for your fuge/filtration needs and add add'l turnover via closed loop or PH's. If you have the room, I'd suggest the closed loop. I've lost 2 anenomes, some Xenia, and Anthelia to PH intakes and will be replacing mine with a closed loop solution soon.

 

[f14peter]

A key point here is to not confuse turnover GPH with pump return GPH, they're two different things.
I think fender and Bacardi explained it well. Stingrayman's systems appears a bit unique, at least compared to the typical system, but it looks like it suits that particular arrangement quite well due to the very high drain capacity (far more, I think, than the average tank).
Return pump GPH must be balanced against whatever GPH is leaving to the tank to the sump/fuge. As I understand it, you want your return GPH (Factoring in headloss) to be fairly close to, but not in excess of your overflow GPH.
My 90g has a 700GPH Mag7 which gives me just under 500GPH at the head, pretty close to the 600GPH drainage on my overflow. Turnover is augmented by two 295GPH MaxiJet PHs (And whatever the skimmer gives me, if that counts) putting right in the neighborhood of 10x turnover recommended for a FOWLR.
4) Bigger pumps generate more heat, use more electricity, cost more, make more noise.
While certainly larger pumps use more electricity than smaller ones, I have read here that larger pumps use less power per GPH than smaller ones, but I don't know that for certain.