The Pools Scientific Guide to Closing Your Vinyl Pool

Most people think of a vinyl liner as the fragile part of the pool, the thing you eventually patch or replace no matter what you do. That's true as far as it goes, but it misses the bigger point: a vinyl liner's biggest enemy isn't a sharp toy or an aggressive brush. It's what happens to the water sitting against it every winter, and almost nobody manages that water with the liner's actual structural dependence on it in mind.

Inside, you'll find the real physics of why a vinyl liner needs water pressure to hold its own shape, why there's a hard structural limit on how far you can ever drain a vinyl pool regardless of cover type, and why going below it risks the liner itself rather than just the chemistry.

You'll get the complete closing protocol: water chemistry in the right order, the correct water level for your specific cover type, the ASTM-rated safety cover distinction that matters more than any chemistry number, and the equipment blowout warning that prevents both an injury and a repair bill. A full closing checklist and quick-reference tables are included for use every season after your first.

Written by John Cooper, a nuclear engineer, U.S. Navy submarine veteran, and the founder of Pools Scientific, a premium pool service platform built on real science rather than industry guesswork.

This is one of four guides in the Pools Scientific winterizing series, above ground, vinyl liner, fiberglass, and plaster pools each get their own dedicated book, since no two pool types hold onto winter the same way.