Question 2, water flow and designs for reef tanks

[Aquattro]

I'm using 2 Tunze streams in my 75, each at opposite back corners point diagnally across the tank. This give me oe dead spot which is a bare patch of bottom, so when I do water changes, I siphon the crud from this one spot.
I also have about 600gph from my return in a sea swirl, but that much flow from a 1" pipe is amost nothing.
One thing I notice is that the corals that are closer to the direct stream of flow tend to grow faster than others with less flow.
It also gives the fish some exercise when swimming around mid tank.