It's really up to you. For me personally, I have over 1200gph in my 50 gallon tank. I have two (500 gph
) placed on the top left blasting towards the right. They face up towards the top of the water to help with the oxidation and create ripples. For whatever dead spots I have (the bottom left of the tank right under the two powerheads) I place a slower ph
to blow in that direction. Just make sure there aren't any dead spots (which I still have, but too much rocks to create a fully circulated tank). Oh yea, my tank is barebottom which is why I can do that. If you have sand there is a higher chance that there are going to be some sandstorms.
Did I mention that I think I still need more flow?
A lot of the poop from the fish fall into some caves and the bottom, need to point another ph
there to make sure it doesn't stack on and on.