yea i had that concern right after i posted. So i have a 30 gallon tank, they say 3 to 5 times the volume of the tank should be the flow through your sump/fuge. I have a 20 gallon H that ill be using for that and the smallest overflow i can find is rated at 300 gph. If i use a ball valve to slow it down, how hard will it be to match to my return pump. I have not gotten one yet, so if you can recommend that to it would be great. Its gonna have about 4 ft of head height.