Maintain your A375UV's bacteria-eliminating effectiveness by replacing burnt out UV bulbs. A375 UV Lamps can ordinarily be used for up to a year before needing replacement.
Be sure to replace your lamps in a timely fashion. Even though the lamp is still glowing, it may not be emitting enough UV light to neutralize bacteria trapped in the filter. As UV light is invisible to humans, it is not possible to determine a bulb's effectiveness by visual inspection alone.
Please dispose of lamps according to local regulations. Spent UV lamps are usually classified as chemical waste and require special handling and disposal.