For ponds up to 4000 gallons. The 4000 gallons rating assumes the unit is being used as a clarifier (algae) only and not as a sterilizer.25 watt T5 UV lampIn lineConnections: 2" slip connectionRequires an approx. 1,200 gph pumpDimensions: 26" X 4" X 2.75"Ballast separate from unitUse the 3/4" Bushing-Hose Barb Kit for use with 3/4" hose