Id run a seperate pump for a closed loop. You will get lots of circulation and water movement without having powerheads in the tank.
From your overflow I would put the drain line(s) into the filter side of the sump. Have a pump returning the water from the sump to the tank with a T fitting and Ball Valve to regulate water flow into the Fuge side of the sump. You could also put a T to the 2 seaswirls as well. I'll up a diagram in a minute...
