The Pura UV36002018 Compatible Replacement UV Lamp #20 is the heart of the Addon-3, UV20 & UVBB systems, which can disinfects up to 3 gallons per minute, when prefiltration is effectively maintained. It is also important to replace your quartz sleeve if damaged or if it cannot be cleaned by non-abrasive methods. 

Replacing your Pura UV Addon-3, UV20 Series & UVBB Series Lamp every year is important to ensure consistent water quality. Though UV lamps rarely burn out, they will lose their ultraviolet effectiveness (disinfection power) over a 12 month period.   
If it is time to replace your Quartz Sleeve:

• Use #20 Quartz Sleeve with Addon-3 & UV20 Systems
  
• Use #22 Quartz Sleeve with UVBB System
  
• Recommended to replace your 36002018 UV Lamp every year