TheGUARDIANUltraviolet Monitorvisually indicates the level of germicidal ultraviolet energy that penetrates the quartz sleeve and water within the water purifier. The use of an ultraviolet monitor is recommended by the United States Public Health Service in Criteria for the Acceptability of an Ultraviolet Disinfection Unit.

TheGUARDIANUltraviolet Monitorwill detect reduction of ultraviolet levels due to:

• Fouling or deposits on the quartz sleeve.
• Poor ultraviolet transmission through the water. Color, turbidity, and organic or other impurities in the water can reduce or interfere with the transmission of ultraviolet rays
• Lamp outage, component or power failure
• Depreciation of the lamp output due to usage or other cause. Lamp output gradually depreciates with use. Lamp replacement is recommended once a year or every 10,000 hours.