Help With Flow... Powerheads?


New member
Hello all,

I have a 40 breeder that I'm just starting to get going.

I have a question about flow.... I ordered some powerheads from Amazon, and I think I ordered the wrong ones haha... They are 800 gph each, and when I turn them on, my clownfish go WHEEEEEEEE! Haha.... I turn them back odd immediately because I fear hurting her!

My question is, are these overpowered for my tank? (I suspect they are....) and if not, how do I go about placing them correctly?

Thank you!

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Well-known member
It sorta depends on what your plans are for the tank.

As a general rule of thumb, 10-20x for fish only (FO/FOWLR) or soft corals. LPS will like something in the 30x+ range, and SPS can go way higher than that (60x or more).

My 120DT is a SPS dominate mixed reef (some LPS, a couple mushrooms and zoas) I use 2 x maxspect gyre 250's on either side of the center mounted overflow, a pair koralia 1500gph powerheads in in the back corners pointed up and in towards the center, and a 850gph koralia in back on one side panel just to make sure there are no dead spots behind the rocks. Everything is controllable. At it's peak, I'd guess 80 or 90x with an average of 60-70x. I don't include my return pump in the numbers at all (eheim 1262)

Your two 800gph powerheads put you at 40x. Just as important as total flow rate is avoiding dead spots where detritus can collect. If you notice that happening, either redirect one or both PH's or do like I did and add another.



New member
I'm running a DCP 8000 and a SW20 both full blast and I'm probably going to add another SW20 to deal with dead spots so no you don't have too much flow. My clown is fine.

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New member
I was being afraid, I see now that it's all good! I got a jebao wavemaker that absolutely pushes the water HARD haha. My fish are dealing with the flow just fine [emoji23]

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