Best Pool O-Ring Buyer's Guide

Most pool equipment failures trace back to a $5–$15 rubber o-ring. Knowing which o-rings to keep on the shelf and which sizes work in which fittings prevents emergency runs to the pool store mid-summer. Here’s the universal o-ring guide for residential pool equipment.

O-ring basics

Pool o-rings are made of one of two rubber types:

• Buna-N (nitrile): the standard. Works for most pool applications. Avoid extended exposure to pool chemicals at high concentration.
• EPDM (ethylene propylene): better for high-temperature spa applications and ozone systems. More expensive.

The five most-needed pool o-rings

1. Pump lid o-ring — the #1 most-replaced o-ring on any pool pad.
2. Pump body o-ring — between the wet end and motor seal plate. Replace anytime you separate them.
3. Filter body o-ring — between the upper and lower halves of cartridge filter housings.
4. Heater header gasket / o-ring — between the heat exchanger and the manifold.
5. Salt cell union o-rings — between the cell and the plumbing unions.

Universal pool o-ring sizes

Most residential pool o-rings come in standardized AS568 sizes. The most-used:

• 5-1/8″ ID Buna-N (Hayward VL Series pump strainer lid)
• 4-1/8″ ID Buna-N (Hayward Super Pump lid)
• 2-3/4″ ID (multiport valve key)
• 9-1/4″ ID (filter body)
• 1-3/4″ ID (salt cell union)

O-rings and gaskets in stock

How to extend o-ring life

• Always use silicone-based pool lubricant. Petroleum jelly destroys rubber. See our petroleum jelly article.
• Replace at every disassembly. The 30 seconds to install a new o-ring saves you opening the equipment again next week.
• Lubricate, then install. Dry o-rings tear during installation.
• Inspect annually. Cracks, flat spots, or dry-rot mean replacement.

For specific o-ring fitment to your pump, filter, or salt cell, send PST Pool Supplies the equipment model number and we’ll match the exact o-ring.