Suprised Noone has mentioned siccie I have the syncra 5.0 and i love it.1375 gph I belive and had been running for 3 yearswith no problems.I do wish they will make a bigger
Sicce has a line of High Flow pumps. Do a google search for Sicce Syncra High Flow and you should find them. I think the largest one puts out a little over 4,600GPH at 0' head.
They are expensive though. I would go with a Laguna...more bang for your buck.