3/4" return and 1" drain is more than enough a mag 5 or 7 or something equivalent to that sould work out. If you make a durso stand pipe you'll get about 800 gph thru the drain otherwise its about 600 gph for an 1" drain. the mag 5 or 7 has a 1/2" return fitting but you can make the hose bigger to get more flow.