In the plans to build a 140gal. plywood tank, would a 50gal. rubbermaid be a good size for the sump? Also I have seen a DIY wet-dry filter layered with ALOT of scrubbies on top and broken-up pieces of brick on the bottom(im guessing in place of ceramic bio-balls)Would this work just as good? Also I am making my overflow with 1 inch pvc, still not sure on my return pump yet. Does all this sound like it would work so far???