2 mp40>1mp60 i personally dont like just 1 powerhead even a vortech corals do much better and flow looks better if you got 2 vortechs instead of 1 big one and 2 40s is about the same price range as 1 60 same with mp10s if any1 is debating a 40 id advise 2 10s(chris) .
i use 1 mp10 and a koralia3 on my 40g and corals love it i get really good extension on my acros