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Closing a UV and salt pool is not just a cover-and-walk-away job. The water still needs to be balanced, the salt cell needs protection, and the UV chamber should be cleaned before scale, moisture, or trapped debris sit there for months.
The best closing plan separates chemistry from equipment. Balance the water first, let it circulate, then shut down and winterize the salt and UV hardware after you know the pool is clean, clear, and stable.
Start with a full closing test
Test free chlorine, pH, total alkalinity, calcium hardness, cyanuric acid, salt, and water temperature before you add winter chemicals. Salt systems often leave pH high near the end of the season, and high pH can encourage scale on the cell plates and UV quartz sleeve while the pool sits covered.
Use the Pool Chemical Calculator website or Pool Chemical Calculator app to size acid, chlorine, alkalinity, calcium, stabilizer, and salt adjustments from real pool volume instead of guessing from the bottle.
Balance water before lowering the level
Make the final chemistry adjustments while the pump can still circulate the whole pool. Bring pH into range, correct alkalinity gradually, and avoid adding extra salt unless the pool will remain open long enough for the cell to use it. If the pool is about to be partially drained, salt readings can wait until spring start-up.
Brush walls, steps, ladders, benches, and corners before the final filtration cycle. UV sanitation only treats water moving through the chamber, so biofilm and debris left on surfaces can still create demand under the cover.
Clean the salt cell and UV sleeve
Inspect the salt cell after power is off and plumbing pressure is released. Remove visible scale with the manufacturer’s recommended method, and avoid unnecessary acid washing if the plates are already clean. Every acid wash can shorten cell life, so inspection matters.
For the UV system, check the quartz sleeve and lamp area. A cloudy sleeve reduces UV transmission, and a damp chamber with debris inside is exactly what you do not want sealed up for winter. Replace worn O-rings before reassembly if they look flattened, cracked, or swollen.
Protect equipment from freeze damage
Drain water from the pump, filter, heater, salt cell housing, UV chamber, chlorinator, and exposed plumbing according to the equipment manuals. Use winter plugs, unions, and air where appropriate for your plumbing layout. Do not leave water trapped in the UV vessel or salt cell body in freeze-prone climates.
Label plugs, unions, drain caps, and sensor cables as you remove them. Spring opening is faster when every part has a home and the salt flow switch or UV lamp connector is not hanging loose near standing water.
Stock the right closing supplies
Useful supplies include a complete pool test kit, salt test strips or a salinity meter, winter plugs, cover hardware, non-staining closing chemicals, a cover pump, filter cleaner, O-ring lubricant, and replacement O-rings for equipment you know is aging.
Shop salt pool closing kits, winter plugs, cover pumps, and testing supplies on Amazon.
FAQ
Should I add salt before closing a UV pool?
Usually no. If the pool is about to be winterized or partially drained, wait until spring to confirm salinity and add salt. Balance pH, alkalinity, chlorine, and calcium first.
Does the UV lamp need to come out for winter?
Follow the system manual. In freeze-prone areas, the chamber should be drained and protected, and the lamp/sleeve area should be clean and dry enough to avoid damage.
Should I acid wash the salt cell at closing?
Only if inspection shows scale that needs it. Unneeded acid washing can shorten cell life, so rinse and inspect before using acid.
Can UV replace chlorine during winter closing?
No. UV only treats water that passes through the chamber. The covered pool still needs properly balanced water and an appropriate chlorine level at closing.