I am gettign a custom 65 gallon 36x18x24 and wanted to run about 1,000-1,200 GPH flow...I was going to go with a 4x5x4 overflow with durso pipe into a 1" drain ...I am now thinking I need to go with a 1.5" drain and a bigger overflow...I plan to run a Mag 12 or 1800 pumping into 2 3'4 return back into the tank. The tank is a short tank so didn't know if it would make sense to hav a big center overflow or on overflow on each side with 1" drains...what do you guys think?