I have a 20 gallon and am setting up a 10 gallon refugium/sump. I am a little hesitant on drilling my tank so I am going to go the external overflow. My question is I am going to get the eshopps nano overflow that is rated @ 200gph. My main concern is what would be a good return pump to match this overflow? From where the pump will be sitting to the top of my tank is about 3.5'. I just don't want to make the mistake of getting the incorrect pump.