Ok a think I know what im sort of doing with sumps now except a basic question. This is for a overflow sump. If you have a pump pushing 450 gallons of water back to. Your tank what size pipe would you need ? Because if your pipe is not suking 450 gallons back down to the pump the whole tank would over flow? Because theres to much water entering the tank and not enough going out the tank?. Thankyou!!