Thanks waterbear. My neighbor, who got rid of his pool last year, gave us his sand filter and pump. I've been reading on here that you can have a pump that has too much horsepower. I don't know the size of the filter (holds 6 bags of sand) or pump. I want to know if it is possible to have too large a filter for a pool (my pool is 5000 gallons) and what would happen if the pump I have is too large for my pool? Can it hurt? These were free and I would hate to not be able to use them, especially considering my pool is green and will be for the foreseeable future.