My return line is 1 inch I think. There are 2 1inch arches pulling water from the tank. The tank is 125 gallons and my sump is like 25 gal. I think. I fixed the over flow problem I had before. Now if I loose power there is little to none lost. But night before last my hose on my new pump blew off, because of a valve I had to install to slow the flow. I should have used hose clamps. Which I did last night and so far so good.