I'm no expert but I have found that the more flow you have the better. In my 36g I have 2 500gph power heads and the return from my fluval 306 canister filter and a fluval hob
filter. On my 90g I have a 1,500gph a 1,250gph and a 1,150gph power as well as the return from my sump. Before I goet as much flow as I have now I had a bit of a problem with little bits of red growth but it has gotten better now.