Pentair Black O-Ring | Sta-Rite Posi-Flo II Cartridge Filters | WC9-3 Drain & Suction Covers Each pump requires two (2)

Each pump requires two (2) of these unions — one on the suction side and one on the discharge side

needing only the minimal amount of sanitizer

Nozzle interchangeability allows custom jet placement

Balance pool water: pH 7

Pentair Black O-Ring | Sta-Rite Posi-Flo II Cartridge Filters | WC9-3 Drain & Suction Covers Each pump requires two (2)The Pentair WC9 3 is the OEM replacement black O ring for Sta Rite Posi Flo II pool and spa cartridge filters, keeping the filter housing sealed and operating at full efficiency. IMPORTANT: LUBRICATION REQUIRED SOLD SEPARATELY Always lubricate this O ring with a silicone based lubricant before installation. We carry the Pentair R172351 Lifeguard Silicone Lubricant the OEM matched product for Pentair equipment. This O ring maintains the pressure seal