Just for referance, I have a 75 gallon with an overflow. I use a Mag 7 as my return. Some of the return line in recycled into the sump so the pump is unrestricted. I am not sure of through put of the whole loop but I would guess is would around 5 times an hour. I kind of like the a slow/low flow since half of my sump is fuge. The trick is getting everything balanced. I wish I wish I had went bigger on the sump just for more room for equipment. When your ready to design/build the sump, give a shout. There is a lot of little tricks.