I have a 20 gallon Tall planted tank and I am seeing debris settle one side of my tank. I have an aquaclear 50 on the tank as a filter with a sponge pre filter to stop my favorite snail from committing suicide. I am thinking about getting a powerhead to help increase circulation and to get more of the debris to the filter. I do not have a good idea of how much flow I might need. I do not want the power head to be huge and obtrusive either. Does anyone have any recommendation on a size or brand of powerhead that might be appropriate for this size tank?