I'm setting up a new cichlid tank and wanted to set-up an Undergound Jet system for it. The tank is 120 gallons and are going to use 3 rio 2100's with Marineland sponge filteration kit. One question I have is on the size diameter PVC pipe I should use. I'm not going to epoxy it to the bottom, just going to use some rock(150-200lbs) and the substrate(Eco-Complete African Cichlid Substrate ) to hold it down. I think that should be enough pumps and water flow for a 120gal. Any input or suggestions would be helpful .