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How many GPH via powerhead should my 30g be getting

Aug 10, 2006
I'm gonna be setting up a new octo tank w/ live rock and was wondering how many GPH on average I should be pumping with a powerhead? Also, woiuld it be more efficient to have one stonger powerhead or 2 smaller ones.

Well, if you are setting up a thirty gallon, you would have to be using for one of the dwarf species, so two smaller heads would be better. A 30 just isn't big enough to handle the waste output of a vulgaris or a bimac.
I would go with two RIO 200's, and make sure you screen them off well, as those little octos can get their arms ripped off easily.
It also depends on your system design. If theres a sump, overflow, how your rockwork is like...etc.

I try to design the tank, so the flow will limit the amount of detritus settleing in the tank. You want the waste to goto the skimmer/filters and not settle somewhere else in the tank.
My system design is pretty basic. No sump or overflow. I have a hang on the back skimmer and mechanical filter. I haven't added live rock yet. I'm just trying to plan ahead for when I revamp my tank which is why I don't want to have to guess on the GPH, or how many powerheads I need to achieve that GPH.
Everyone chime in here....I am intested in everyone's opinion.
but my understanding is that the gph flow rate of powerheads that are unattached to any filtration is immaterial.

Reef tanks that rely on live rock must have flow over larger areas of rock to be sure the live rock comes in contact with the most water volume to denitrate it. I can see it is important to make sure that there is minimal detrius sitting on the bottom. But this is a lower rate than the current philosophy in reefkeeping.

I see benchmarks in filtration systems being:

1.the amount of dissolved oxygen in the water. This can be done with a good skimmer and a wet/dry.

2. The amount of flow over the filtration media for waste removal. This is the same no matter what type of filtration you use (canister, power, trickle, etc.) This would relate the to amount of waste that can be processed, factored by the pros and cons for the type of filtration used.

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