Well the closed loop is supposed to be somewhere in the neighborhood of 700 gph. The fuge pump broke on me a while ago (Rio) and the only other pumps I had were all mj1200s, so i stuck one on there. That really moves the surface around.
Actually, I had to redirect the cl outputs to not blow the surface around so much...it was really messing with my ATO system.
I still wish I had gotten the next size pump. It's easier to close off the flow a little than try and scrounge more.