ok so I'm getting tons of settlement in between my rocks... I know I need more flow in my tank, but lately I'm taking a powerhead and blowing through the rocks and stirring it all up. But the problem is I don't think my overflow is working the best, because it all just goes right back down to the sand and I'm getting "moldy" sand as the kids call it. Would I be better off getting like 2 overflows and a stronger return or drilling more whole in my overflow? I guess I can get a bigger one huh.. is that even the problem?! or if I had stronger powerheads the constant movement would eventually fix the problem?