Algreen PressureFlo 2000 Mechanical and Biological Filtration for Ponds/Fountains/Water Features and Gardening Algreen Mechanical and Biological Filtration Helps Maintain Clean and Healthy Pond Water with In/Out Valves for Simple and Quick Cleaning Integral Ultra-Violet Sterilizing Clarifier Permanently and Continuously Controls Algae Ideal For Water Filtration of Large Ponds up to 2/500 Gallons Includes 2 Year Warranty and is U.L Listed