Pool seals rarely die under load. They die in November, compressed in one position, cold, and stay that way until April. What you do at closing decides how much of spring you spend chasing leaks.
Why winter is what kills o-rings
Rubber held under constant compression at low temperature takes a permanent set — it stops returning to its original shape. A ring that was serviceable in September can be a flat, hard band by April.
Add freeze-thaw. Water trapped in a groove behind an o-ring expands as it freezes and can distort the housing as well as the seal.
At closing
1. Drain everything that holds water
Pump, filter, heater, chlorinator. Any water left in a housing can freeze, and the damage will be to a plastic casing rather than a rubber ring.
2. Remove drain plugs and store them with the pump
Leave them out over winter so the housing cannot trap water. Put them in the pump basket so you can find them. Replace their o-rings at opening as a matter of routine.
3. Lubricate lid and union o-rings — do not leave them dry and clamped
A film of food-grade silicone slows drying and helps the ring stay pliable. Better still, back off the lid so the ring is not compressed all winter. That single habit meaningfully extends the life of the most frequently replaced seal on the system.
4. Inspect while it is apart
Closing is the natural moment to look at every ring. Hard, flattened, cracked or glazed means order now — not in April when everyone else is ordering too and you want the pool open.
5. Note what you found
Write down the model numbers of anything you will replace at opening. Photograph the motor plate. Come spring you will not remember, and a corroded plate is harder to read after a winter outdoors.
The chlorinator deserves special attention
Do not leave tablets sitting in the feeder over winter. The lid o-ring will spend months in concentrated chemistry with no water flow, which is the worst case for it. Empty it, rinse it, and if the seal is Buna-N consider replacing it with FKM — see why chlorinator o-rings need FKM.
Order in autumn, not spring
The seals you know are marginal will not improve over winter. Ordering in October costs the same as ordering in April, and means opening day is a morning's work rather than a week of waiting.
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.