Some folks go the "extra" step and instead of using powerheads they will get a larger pump and plumb into the tank a closed loop. Basically all a closed loop does is pull water out of the tank into the pump, then it's pumped back into the tank through multiple nozles. This Accomplishes the same thing as powerheads, but instead of having 3 or 4 big hulking pumps visible in the tank you have one "pipe" that draws water out of the tank, then just a couple of nozzels that barely break the surface of the water that return the water to the tank. And the pipe and nozles, like darb2 mentioned, will become covered by coraline and other algaes and will quickly become less obvious.