im going through on HECK of a time tryign to pisition my powerheads just right os i dont get these drifts im getting, my sand in one spot is abotu a queter inch and in others it is 6 inches...its only happening in the middle and right side of the tank the left is perfectly flat, but thats where my return is(on the left) i might t-out my return and put another return in the right corner also so it might evan the flow out a bit. i have two powerhead hidden in my live rock on the left and the right(one in each corner)..i keep playing with them but no luck, they are rated at almost 1000 gph each i have about 12 times turn over rate, but i think i might beef my return pump up and go with 20...any suggestions?