I've found that when using high volume pumps (closed loops, Streams), a great way to manage a lot of flow is to bank it off the glass. You lose some of the direct velocity, but it creates very random currents - you can get behind and under rocks in ways not possible with outputs blazing right over the rockwork. Of course this can play havoc with sandbeds, but...
I don't have that issue.
I no longer use wavemakers, because I've found that I can get the same overall effect by doing this. The added benefit is that the pumps are always on, so a constant amount of water is always being moved, but the corals are not always getting blasted. FWIW...