Something in the 550-900 gph range after head. If you mean controllable with the apex there are not many reliable options out there. And they are $$$$. Not even sure if they would work with apex, but abyzz and bubble king dc are controllable and reliable. A few new dc pumps look promising like ecotechs and maybe neptune iirc? No real reason to control a return though. Lagunas are my favorite, rock solid and affordable. Followed by fluval sp series, same pump but with ceramic bearings, a stand and different coupling method, also more expensive. Eheim would be another but you might need to run two to get that flow depending on head.