Never drain an above-ground pool below about a foot of water. The water is what braces the walls and keeps the liner stretched — an empty pool in winter is how liners shrink and walls buckle.
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The closing order
1) Balance the water — pH 7.4–7.6, alkalinity 80–120 — while the pump still runs. 2) A day later, raise chlorine to about 10 ppm (the closing kit calculator sizes it to your gallons). 3) Add winterizing algaecide once chlorine drifts below 5. 4) Clean the pool thoroughly and remove every ladder, skimmer basket, and floating toy. 5) Drop the water to the level above. 6) Disconnect and drain the hoses, pull the pump and filter plugs, store them inside. 7) Pillow in the middle, cover over it, cable and winch snug, clips on if it's windy.
A solid cover keeps precipitation out, so the level you leave is roughly the level you find. A mesh cover passes every drop of rain and snowmelt straight into the pool, which is why it starts so much lower — get that wrong and you spend March pumping out an overflowing pool that has floated its own cover.
The pillow is the whole trick
Ice expands about 9% by volume, and it expands toward whatever gives first. With a pillow floating in the middle, that's the pillow. Without one, it's your walls — which is the difference between a $15 part and a new pool. Inflate to about two-thirds, tether it toward the center, and don't be alarmed if it deflates by February; it has usually done its job by then.
Sizing the cover itself is the cover size calculator, a solid cover wants a cover pump on it all winter, and when to close answers the question this page assumes you've already settled.
Frequently asked questions
How far do I lower the water to close an above-ground pool?
Less than most people think. With a solid cover, 4–6 inches below the skimmer mouth is plenty. With a mesh cover, go 12–18 inches down, because winter precipitation drains straight through and refills it. Never drain an above-ground pool much further — the water is what holds the walls and liner in position.
Can I drain my above-ground pool for winter?
No. An empty vinyl pool is a structural problem, not a clean one: the liner shrinks and hardens in cold air and won't stretch back in spring, and the walls lose the water pressure bracing them against frost heave and wind. Every above-ground pool overwinters with water in it.
Do I need an air pillow under the cover?
Strongly yes, and it's a $15 part. The pillow gives the ice sheet somewhere to expand — as water freezes, it pushes in toward the compressible pillow instead of outward against your pool walls. Inflate it about two-thirds, never fully; a drum-tight pillow just splits on the first cold night.
Do above-ground pools need the lines blown out?
Usually not the way inground pools do. Most above-ground plumbing is a short run of flexible hose between the skimmer, pump and return, which you simply disconnect, drain and store. The parts that matter are the pump, filter and any heater — pull their drain plugs and keep them somewhere dry.
Should I take the pump and filter inside?
Yes, where you can. Drain them fully, pull every plug, and store them out of the weather — freezing water in a pump housing cracks it, and that's the most expensive avoidable loss of the winter. Keep the plugs in the pump basket so April doesn't start with a hunt.