Assuming you are talking about a powerhead for circulation and not a sump pump, like a Mag, then it sort of depends on what you plan on keeping. The Rio won't be too much for
LPS's or softies as long as they aren't positioned directly in front of it. If you plan on having any
SPS's, one isn't enuff.
I personally recommend the new Hydor Koralias. You get a real nice WIDE flow as opposed to the strong narrow flow from a normal powerhead. I have 2 Koralia 3's (850
gph) and a RIO 600 (200
gph) for circulation in my
SPS dominated 75.