The PondPro Multistage Pressure Filters provide both mechanical and biological filtration processes that are essential to the health of your pond. Large system capacity, and foam surface area provides excellent filtration by allowing the increased growth of beneficial bacteria. Pressurised systems are ideal for waterfall applications. The unique external pressure indicator shows green light when filter is performing properly, and shows red light when filter cleaning is necessary, taking the guess work out of pond maintenance! Includes an easy-to-use backwash rinse system.