Keep your Clean Pond Machine 16,000 in working order with this UVC replacement lamp. Your UVC lamp should be replaced every season, ideally in the early spring, to prevent green water algae in your pond. This bulb can also fit other pond filters that require an 18w PLS bulb. Specifications: 18w PLS – 169mm 2 Pin. Please note - these bulbs are intended for use in filters and clarifiers and should not be used as lighting.