A pond UVC exposes your pond water to powerful UV rays. These rays cause the microscopic algae to flocculate (stick together) and form larger particles which sink to the bottom of the pond, get picked up by your pond pump and then get caught in the pond filter sponges. Dimensions: * Length: 31cm * Width: 8.5cm Voltage: 220-240V/50Hz UVC power: 18w (single-ended) Power cable length: 1.5m to transformer; 5m from transformer to UVC Guarantee: 1 year Maximum flow rate: 7,500lph Inlet/outlet sizes: 20/25/32/40mm