How often should I replace the UV bulb in my UltraKlean Pond Filter? April 18, 2026 02:38 Replace every 12 months at 24-hour operationBulb may last:2 years at 12-hour setting4 years at 6-hour settingEven if lit, UV output declines over time. Related articles Videos and Troubleshooting How often should I backwash my UltraKlean Pond Filter? How do I backwash my UltraKlean Pond Filter? UltraKlean Pond Filter Winter Maintenance