AH-UV12-L Replacement Lamp / Bulb for 12W UV Ultra Violet Water Sterilizer. AquaHouse replacement UV Lamp / Bulb model AH-UV12-L – for use in the 12W AquaHouse UV Sterilization System (AH-UV12). This UV lamp / bulb will last for approximately 9000 hours between changes (1 year). Replace the lamp/bulb when the power supply transformer light indiciator changes to show when the bulb has expired / in the rare event of bulb failure, for complete peace of mind.