Fish go through a lot in the ocean, the currents are very swift. I really don't suspect then added currant is a sole contributor. I had a 55g fish tank where I had 1-1050 1-750 and 2-550 korallias and it wasn't enough currant for my liking, so 2 1050's aren't much for a 75g. If you suspect that you have to much flow, and I really don't think its a problem, cut one of the power heads for a while and observe the fish. I think its being subjected to something else. What is the fish doing? When you hooked up your ph's did you notice a lot of debris floating around? I would recommend checking your levels to make sure you spike your levels.