Pondmaster UV Replacement BulbPondmaster UV Replacement Bulbs is the replacement UV Bulb for the Pondmaster UV Clarifiers. Average "Useful Life" is 9000 hour A good rule of thumb is to replace every year at the beginning of pond season for best results! Replacement UV Bulb for Pondmaster UV Clarifiers Average 9000 hour "useful life" Replace yearly for optimum pond clarification 10, 20, 40 watt UV bulb Quantity 1 per package. Clean or Replace Quartz Sleeve when replacing UV Lamp.