Is 840 gph too much for a 20 gal long?

[Romann]

Its divided up by 2 powerheads and a hob filter. I plan on keeping LPS and softies only as of right now.

 

[mcgyvr]

Not really but it is quite a bit of flow
If corals seem ok and you aren't blowing sand all over the place then its usually fine..

 

[billdogg]

That's just over 40x turnover. It could actually be too much for some softies and very fleshy LPS unless you can find those specimens a place with a bit less (up against the rocks, etc) If it were a SPS tank, I'd probably suggest a bit more

 

[dorry54]

i would lower it

 

[mcgyvr]

i would lower it

Why?

In general the more flow the better so long as you aren't blowing the skin off your corals..

 

[McPuff]

You should also consider whether the flow is constant or pulsing/random. If it is constant flow, then your results will not be as good compared to pulsing/random. And with random flow, you can really turn up the flow rates.