Pentair Black O-Ring | Sta-Rite Posi-Flo II Cartridge Filters | WC9-3 Drain & Suction Covers Balance pool water: pH 7

Balance pool water: pH 7

⚠️ IMPORTANT: Remove Pad Adapter Before Installing

Built in cup holder

For excess foaming problems

Pentair Black O-Ring | Sta-Rite Posi-Flo II Cartridge Filters | WC9-3 Drain & Suction Covers Balance pool water: pH 7The 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