I've posted before about using oversized plumbing to decrease head pressure and increase flow rates.I was checking out the calculator at RC and i decided to put my numbers in for my 40 that i just setup.933GPH was what i came up while using 1" PVC,if i would have went with .75" like the pump accepts,it would have only been 710GPH.What a difference,so if you guys/gals are still using 3/4" and want to get some extra flow,might be a good time to upgrade your plumbing.