Saltwater pools get sold on being gentler. On your skin, they are. On rubber, they are not — and ozone systems are harsher still.
What is actually happening
A saltwater pool is still a chlorine pool. The salt cell electrolyses sodium chloride into chlorine on site, continuously. At the cell itself, concentrations are high and generation is constant rather than dosed.
Ozone is a different problem again. Ozone is a far more aggressive oxidiser than chlorine and it attacks the double bonds in standard nitrile directly. An ozone generator will craze and crack a Buna-N seal in a fraction of its expected life.
Add salt's effect on metal — stainless springs and retainers corrode faster in a salt environment — and the standard seal is being attacked from two directions.
What fails, and how you recognise it
- Hardened, glazed rings that have lost all spring. Press one; a healthy ring rebounds.
- Fine surface crazing — a network of tiny cracks. Classic ozone attack.
- Rust on the seal spring where a pool-water seal would still be bright.
- Seals failing on a predictable annual cycle rather than after several years.
That last one is the giveaway. If you are replacing the same seal every season, the material is wrong.
The right specification
FKM fluorocarbon resists oxidisers where nitrile gives up. For shaft seals in salt and ozone service, look for seals specified for it — such as the Waterway Plastics 319-3010/B FKM salt and ozone shaft seal, built for exactly this duty.
The same logic applies to your chlorinator, where concentrations are highest of all — see why chlorinator lid o-rings need FKM.
Where to spend the extra and where not to
FKM costs more. You do not need it everywhere.
- Worth it: salt cell unions, ozone contact chambers, chlorinator lids, pump seals on salt systems.
- Buna-N is fine: filter tank o-rings, most union seals, and anywhere seeing normal pool water at normal concentrations.
Full comparison in our material guide.
Before you reassemble
Seat every o-ring with a thin film of food-grade silicone. Dry rings pinch and take a set — the usual reason a new seal weeps within a season. Aqua Flex Food Grade Silicone Lubricant is what ships in our kits.
O-rings only. Never lubricate the polished faces of a mechanical shaft seal.
Beaver Island Parts Company is not affiliated with, endorsed by, or sponsored by any equipment manufacturer named on this page. All brand names, model numbers and part numbers are the property of their respective owners and are used solely to identify the equipment our replacement parts fit.