[CollegeReefer]

The pump needed all depends on your overflow. You need to take how much your overflow will drop and match that with a pump that can push close to that much water at whatever height is needed. You need to look at the head chart of the pump. Also it is wise to note that you are going to want the pump to pump less then the overflow rather than more for if the pump pumps more it will overflow your main display and drain your sump where as if the pump is less the overflow will only drop the water at the rate of the return pump.