I'm thinking to build a small centrifugal pump to suck in dirts and algae accumulating at the bottom (concrete) of my pond. Commercially available centrifugal pumps are too heavy and too expensive. I plan to use an old but working 1/2 HP induction motor directly connecting the pump. Please help me designing the shape of an impeller (about 4" diameter) and where I can get a sealer and suitable bearing.