How to close and winterize your pool
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Closing a pool protects it from freeze damage and makes spring easy. Balance the water, lower the level, drain and blow out the equipment so nothing freezes, add winter chemicals, and cover it.
Step by step
- Balance the water firstA few days before closing, bring pH to 7.4–7.6, as Trouble Free Pool’s closing guide does, with alkalinity and calcium in range, so the water stays gentle on surfaces all winter.
- Shock, then let chlorine settleTwo or three days before closing, raise free chlorine to shock level (40% of your CYA) and hold it until it holds overnight, which Trouble Free Pool says it usually does the first night. Then let it fall to 20% of your CYA, typically another day and a half.
- Lower the water levelCheck your cover’s instructions first: an automatic cover needs full support and a safety cover specifies how far below it the water can sit. Otherwise Trouble Free Pool lowers a plaster pool to about 4 inches below the bottom of the returns and a vinyl pool 4–6 inches below the skimmer.
- Drain and blow out the equipmentBlow the lines out until only a fine mist comes from the other end, then install winterizing plugs. Remove the drain plugs on the pump, filter and heater, and pour pool antifreeze on top of the skimmer plug. This is the step that prevents cracked equipment.
- Add algaecide and coverTrouble Free Pool adds the startup dose of polyquat algaecide from its label, removes the skimmer baskets and return fittings, and covers the pool, weighing the edges down with water bags.
FAQ
When should I close my pool?
Wait until the water is solidly below 60°F (15°C). Trouble Free Pool’s closing guide notes that below 60°F algae is unlikely to grow and grows very slowly when it does, so closing while the water is still warm invites algae under the cover.
Do I need to drain my pool to winterize it?
No. You only lower it below the skimmer and returns on an in-ground pool. Fully draining can damage the pool or float a liner and is almost never needed.
Can I leave my pool running all winter?
In mild, sun-belt climates that never freeze, many owners keep the pump running instead of closing. Closing matters most where the plumbing can freeze.
Sources
- Trouble Free Pool, Closing an In Ground Pool. Closing temperature, pH, shocking and chlorine level, water level, blowing out lines, drain plugs, antifreeze and polyquat
- Trouble Free Pool, CYA Chlorine Relationship (Chlorine/CYA chart). Shock level as 40% of CYA
Related
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