Close the pool once the water has cooled for the season, not on the first cool weekend. Algae keeps growing in warm water under a cover, and a green pool in spring takes far more work than another week or two of running the pump.
This checklist is for an outdoor pool going under a winter cover somewhere that gets freezing weather. The details change with the pool. An above-ground pool and an in-ground pool drain and plug differently, and a mesh safety cover and a solid cover need the water at different levels. Your pool, pump and cover makers’ instructions win wherever they disagree with this list.
Shock the water first and add the winter algaecide later, once the chlorine has come back down. Strong chlorine can break down some algaecides if you add both at once.
- Check the winter cover for tears and find all its parts — That means the water bags, anchors or cable that hold it down. Find out now if you need a replacement, not on closing day.
- Buy a closing chemical kit for your pool's size and winter plugs that fit its returns and skimmer
- Test the water a few days before closing and balance it — Adjust pH, alkalinity and calcium hardness to the ranges on your test kit or chemical labels.
- Skim, brush the walls and vacuum the floor — Leaves left on the floor stain the surface over winter.
- Shock the pool and keep the pump running
- Add the winter algaecide once chlorine is back in its normal range — Follow the product label for timing and dose.
- Clean the filter — Backwash a sand or DE filter. Hose off or soak a cartridge.
- Remove ladders, handrails, skimmer baskets and return fittings
- Clean and dry them, then store them out of the weather
- Take out the pool cleaner and store it indoors
- Lower the water to the level your cover and pool type call for — The right level differs between mesh and solid covers, so read the cover maker's instructions before you drain.
- Turn off the pump, heater and any chlorinator at the breaker
- Drain the pump, filter, heater and chlorinator
- Keep every drain plug in the pump basket — That is where you'll look for them in spring.
- Blow out the skimmer and return lines on an in-ground pool — Hire a pool service for this if you don't have the right blower and fittings.
- Plug the returns and fit a skimmer plug or freeze guard
- Add pool antifreeze to the lines if the maker of your system recommends it — Use pool antifreeze only, never the automotive kind.
- Disconnect the hoses on an above-ground pool and store the pump indoors
- Fit the winter cover and secure it — Don't fill water bags to the top. They need room to expand if they freeze.
- Walk the edge and check for gaps where leaves or animals could get in
- Take photos of the equipment, valves and plug positions — They make opening the pool in spring much quicker.
- Store pool chemicals somewhere dry and away from children, and keep them apart from each other — Some pool chemicals react dangerously if they mix.
- Through the winter, pump standing water off a solid cover and clear off debris