How much flow for sump and in tank?

[ScubaSteve]

Well, that all depends. First of all, what are you keeping? Different livestock have different flown characteristics. I keep mostly SPS, so the flow in my 40 gallon tank is probably close to 1500 gph... So that's what? 35x turn over? But then again i yave a different tank design that really breaks up that flow, so it doesnt seem that high. If youhave softies or LPS you can do much lower. There are no hard and fast rules for flow, do what you need to do so your livestock is happy and you don't have any dead spots in the tank.

For the sump, there is a lot of debate as to the flow. Some people say 10x your total sump volume... So that 250gph. I said screw that and with my new build that I am doing as we speak I am going 500 gph through a 15 gallon sump

[SeaHorse_Fanatic]

I like lots of flow in tank & slow flow through the sump for greater dwelling time.