PondMaster 20 Watt Clarifier/Sterilizer Pondmaster Clarifier Sterilizer 20 Watt Suitable for ponds of up to 3000 gallons using pumps of up to 1800 GPH Submersible or in-line use 20-watt UV water clarifier effectively kills suspended algae, eliminating green-water pond problems Suitable for medium ponds up to 3000 gallons using pumps up to 1800 gph Vortex flow design and slim diameter provides added efficiency; installable in or outside pond Includes 9000-hour 20-watt lamp, transformer, 18-foot power cord, and watertight quartz sleeve Measures approximately 19 by 4 inches; 1-year warranty