Pentair Cartridge 520 sq. ft. | Clean & Clear Plus Filter 520 sq. ft. | R173578 PD165 Backup Valve opens every 3

Backup Valve opens every 3 minutes for 30 seconds allowing the cleaner to backup and change directions

Lime wedge back rest

In-Line (incl 2" inlet and outlet ports) CL2002S Hayward Automatic Chlorine Feeder

or inability to complete a proper backwash cycle

Pentair Cartridge 520 sq. ft. | Clean & Clear Plus Filter 520 sq. ft. | R173578 PD165 Backup Valve opens every 3The Pentair R173578 is the OEM replacement filter cartridge for the Clean & Clear Plus 520 sq. ft. cartridge filter, restoring full filtration capacity to one of Pentair's largest residential cartridge filter systems. IMPORTANT: 4 CARTRIDGES REQUIRED PER FILTER The Clean & Clear Plus 520 sq. ft. filter requires 4 of these cartridges for a complete service. This listing is for one (1) cartridge. Order 4 to complete a full replacement set. IMPORTANT: