Wikishopline ›
Articles ›
Home & Garden ›
Pool Closing Day: The Full Checklist for Above-Ground and In-Ground
Pool Closing Day: The Full Checklist for Above-Ground and In-Ground
The first year I closed a pool myself I skipped the chemistry balance step because I figured I'd deal with the water when I opened it in spring. I opened it to a swamp — deep green, thick with algae, with a filter that had cracked from freezing water I hadn't fully blown out of the lines. The cost to fix it was greater than I'd saved by cutting corners. Closing a pool correctly is not difficult, but each step matters, and skipping any one of them creates a problem you'll meet again in May.
Balance the water chemistry first, before anything else
This is the step most people either skip or do last, and it should be first. Unbalanced water over a winter of stagnation becomes a hostile chemistry environment. You want pH between 7.2 and 7.6, alkalinity between 80 and 120 ppm, and calcium hardness between 180 and 220 ppm going into winter. Adjust with pH adjusters, alkalinity increaser, or calcium hardness increaser as needed based on your test kit readings. Then shock the pool — add a chlorine shock treatment at roughly double the regular rate to kill anything biological before covering it. Add a winterizing pool chemical kit according to the manufacturer's instructions. These kits contain algaecide and other treatments formulated specifically for the closed-season period and they genuinely make spring opening easier. Let the pump run for a full day after adding chemicals so everything circulates completely before you shut things down.Blow out the lines — this is the critical mechanical step
Frozen water in pool plumbing lines is what causes the expensive cracks. It doesn't take an extreme freeze to do damage — water expands nine percent when it freezes, which is enough to split a fitting or crack a pump housing. The sequence: turn off the pump, remove the drain plug from the pump housing and set it somewhere you'll find it in spring (many people zip-tie it to the pump itself). Remove the drain plug from the filter. Use an air compressor or a pool line blower to blow out each line — the skimmer line, the return lines, the main drain line if applicable. You're listening for the air to blow through clearly rather than pushing water. When water stops coming out and you're just blowing air, that line is clear. Plug the return jets with winterizing plugs and plug the skimmer with a Gizzmo or similar freeze-expansion device. If you have above-ground equipment like a heater or heat pump, drain it according to its manual — these are the most expensive things to replace if they crack.Lower the water, remove deck equipment, cover the pool
For in-ground pools with tile lining: lower the water four to six inches below the skimmer to allow for ice expansion at the surface. For vinyl-liner pools: you can leave the water level higher since the liner is flexible, but still clear the skimmer line. Remove all deck equipment that can be damaged by freeze-thaw cycles: ladders, rails, slides, diving boards. Store them inside or in a protected area. Clean the pool net of leaves and debris. This is worth doing even if the cover is going on, because whatever's in the water now will be in there all winter. The pool cover is your primary physical barrier. A solid winter pool cover with air pillow support in the center prevents ice damage to the walls — the pillow absorbs ice expansion laterally rather than letting it push outward. Anchor the cover tightly with water bags or the provided anchor system. A loose cover will collect standing water on top and may blow off in wind.Above-ground specific: the walls need protection
With above-ground pools, ice forming on the water surface can push outward on the walls if there's no expansion accommodation. The air pillow in the center — a simple inflatable bag designed for this purpose — gives the ice somewhere to push. Without it, years of this stress will eventually deform or split the pool walls. Disconnect the pump and filter, drain them completely, and store them indoors. Below-freezing temperatures are genuinely damaging to pump housings even when there's no water in them if the lubricant congeals in certain conditions.What I'd skip
Skip trying to close a pool in one rushed afternoon. The chemistry balance needs time to circulate, the lines need careful blowing, and trying to do everything fast leads to the specific shortcuts that cause spring damage. Block a full half-day and do it in the right sequence. The bottom line: pool closing properly takes four to five hours and costs the price of chemicals and plugs. Pool repair from an improper close can run into hundreds or thousands. The math on doing it right is not complicated. Ready to shop? Compare Home & Garden across stores → 📚 Or browse home & garden guides in Digital Goods →📢 Affiliate Disclosure: This article contains affiliate links. We may earn a small commission at no extra cost to you when you click through and purchase.
