Many pond builders have found that adding a bottom drain helps keep a pond cleaner. Fish waste and other muck that accumulates on a pond bottom can be easily removed by a bottom drain. Ponds that are over 2′ deep can become stagnant without a bottom drain. BD1 - 3-Inch Bottom Drain Increases circulation and cleaning capacity Dual rubber gaskets and six stainless screws for watertight penetration through liner For use with 3″ schedule 40 PVC fittings and pipe. Drain kits to connect to pond skimmer also available BDA - 3-Inch Bottom Drain with Air Diffuser Increases air circulation and cleaning capacity Includes 10″ rubber air diffuser that connects to top section 1/2″ barbed inlet fitting for incoming air Dual rubber gaskets and six stainless screws for watertight penetration through liner For use with 3″ schedule 40 PVC fittings and pipe. Drain kits to connect to pond skimmer also available Also available: 3-Inch Drain Kit Related Products Flexible PVC Silicone Glue