ZENY™ Pressure Bio Filter for Pond 13W UV Sterilizer Purifier Light 10000L Koi Water 4000 Gallons Easy Backwash FunctionStrong Capacity** Powerfull enough to filter up to 2500 Gal with a normal fish load,or 1500 gal with a heavy fish load. It is an efficient filter to purify ponds. UV Clarification** Equiped with UV lights which will a positive contribution in dealing with the algae. Improving the water quality to provide a clear and healthy pond for your fish. Multipurpose** It can not only draw water, but it also can be used to filter the pond with bacteriostasis