Legacy replacement filters (CVR5450) should be replaced annually.
Alternatively, if you own a VistaClear™ System manufactured prior to October 31, 2012, consider talking to your preferred dental distributor about upgrading your system to the "HP" style with a Retrofit System (part number CVR9280).
The Retrofit System includes the necessary replacement elements, makes the system run even more efficiently, and provides a DentaPure™ Cartridge that eliminates the need for regular shocking protocols to make waterline maintenance much more efficient.