ok....so tell me if I'm understanding this.......

a 1200gph return pump from the sump, split off to 2 returns in the tank (2 inputs)....(or I guess I could just use 2, 600gphs...1 on each return....and then I have "backup" if one pump dies while I'm out of town the other keeps running)

a 3000gph external pump (or 2 1500gphs) just cycling water out and then back into the pump through 8-10 inputs.....

if need be, some intank pumps to move extra water around