I had about 16X's per hour on my old system. For me a more important point was varied flow. I had 3 Sea Swirls on the tank and it really provided a nice sway to everything. Click my red house for pics and info.
Agree about hydor Koralia #3 i run 2 on my 55gal pointed towards each other, also, 2 penguin powerheads in the same direction towards the back glass to avoid dead spots and create more chaotic flow around. You should be able ti see your corals sways in different directions, stay still for a second and then away again.