Pool Closing Checklist

With the summer winding down for many of us in colder climates, pool season is coming to a close. Labor Day is usually the last hurrah for swimmers before the kids are back in school and the pool starts to sit empty. If you need to winterize your swimming pool to prepare for the winter months, go through our pool closing checklist to make it easier to open in the spring and to ensure none of your plumbing is damaged in the freezing temperatures.

Balance your Water

Approximately days before closing your pool, balance your water chemistry. This means testing your water to make sure your alkalinity, pH, and calcium hardness are within their ideal target areas. Just as a refresher, the pH should be between 7.2-7.6, alkalinity 80-120 ppm, and calcium hardness between 180-220 ppm.

Shock Your Pool

The next step is to shock your pool with chlorine. Rather than your typical shock treatment that allows you to swim in the water the next day, you’ll need to pick a treatment that is at least 65% sodium hypochlorite (or a non-chlorine substitute of similar strength).

Add the shock granules to a bucket of water and not directly into the pool itself. Add the manufacturer recommended amount of granules to the bucket and make sure they’ve completely dissolved before introducing that bucket into the pool water. Run the filter and watch the water chemistry over the next few days and allow the chlorine level to return to between 1-3 ppm. You won’t want to take the next step if the shock treatment is still active.

Add an Algaecide

To prevent the blooming of algae over the winter, get a winterizing algaecide that will kill the existing algae and stop any more from forming. Algae can stain your pool plaster, will have a harsh smell, and can be difficult to kill off come next spring.

BE SURE that your chlorine levels have returned to somewhere between 1-3 ppm before adding the algaecide, otherwise the extreme amounts of chlorine will kill off the algae-eliminating agent. Add to your pool according to the manufacturer’s instructions and it should keep algae from forming all winter long.

Additional Chemicals

Now is the time when you can add rust and scale preventers or other preventative treatments to your water. It’s up to you to decide if these are something that will make your life easier come springtime.

Clean Up

After you’ve adjusted the water and think it’s getting ready to be covered, it’s time to clean up in and around the swimming pool itself. If it’s not water, it needs to come out of the pool. This includes not only toys, but removable ladders, baskets, hoses, filters, pumps, heaters, and any miscellaneous or decorative fittings.  Take out your bromine/chlorine floater, too, because it may stick to the wall all through the winter and will end up bleaching the surface.

Once removed from the pool, give all the equipment a quick rinse with fresh water and let them dry completely before putting away. Store inside a garage, shed, or somewhere in your home for the winter. Consider having an air/water tight container to put them in to prevent anything from deteriorating over the winter season (and keep any kind of critter OUT).


Brush and vacuum the same day you shut down your pool to be sure it’s clean and ready to be closed.

Use your typical pool cleaning equipment to go through and finish the cleaning process. First, brush the sides and bottom of your pool to scrub off and loosen any unwelcome gunk. After brushing, use either your pool vacuum cleaner (either suction or non-suction) to pick up what you just brushed off and empty out the filter.

If you have a lot of debris at the bottom of your pool, use a skim bag to collect it before brushing and vacuuming.


Be sure your pool water is as debris-free as you can manage to make it before closing up for the summer. Free-floating organic material can stain plaster if it settles on the bottom. Get all the leaves, insects, etc. and be thorough. This isn’t just a casual skim before a swim, it’s the last one you’ll do for the season.

Skimming should be pretty much the last thing you do before putting on your cover.

Lower Water Level

You don’t need to empty your water out of your swimming pool completely, despite some misconceptions. That actually can lead to some damage to your pool and equipment by creating hydrostatic pressure. Just lower the water level with a pump to just below the skimmer, based on the type of pool cover you use over the winter. If you utilize a mesh cover, lower the water level to 12-18 inches below the skimmer. If you’re using a solid, floating cover, it’ll only need to be 3-6 inches below the skimmer.

Make sure all the water is out of the throat of the skimmers so that it doesn’t freeze over during the winter.

Drain Equipment

All of your pumps, filters, heaters, and chlorinators will need to be drained of any remaining water before winter approaches. If your equipment is stored somewhere in an uninsulated garage, freezing water could damage or ruin the mechanics.

To drain your equipment, open the appropriate valves/plugs to release water from the interior and let the water out and allow the interiors to empty and dry. Store everything in an air/water-tight container until you need them in the spring. If you have to remove plugs, put them in the strainer basket to keep them all in one place. You don’t want to reseal the openings after you’ve just cleared them out.

Remove Filter

You’ll also need to remove your filter, clean it thoroughly, and store in a dry place inside during the winter time. If you can’t remove your filter, use something like a shop vac or air compressor to blow out any lingering water.

Winterize Plumbing

The lines that carry water throughout your pool need to be drained and dried so that they don’t freeze and become damaged during the cold winter months. Use a shop vac to blow the air from the skimmer through the equipment and back into the pool. If you have rubber plugs, use these to seal up the lines so that water can’t get back into the lines. Threaded plugs are best, if your fittings allow for it.

If you don’t want to blow out the lines, you can add swimming pool specific antifreeze that will prevent the remaining water from freezing. Follow the manufacturer’s instructions on the bottle. DO NOT use car antifreeze for pool plumbing.

Cover Your Pool

Once everything is clean, you’ve emptied the pool of equipment, and have thoroughly de-debris-ed the water, it’s time to cover it. It’s important that you use a cover that fits properly and doesn’t leave any gaps or cracks open to the elements. Whether you use a safety cover or a solid floating cover, be sure that it’s sealed off. Take some time to look over your cover and be sure there aren’t any tears or holes in it.

Before you cover your pool, you can use air pillows. These are meant to sit in the middle of your swimming pool to absorb pressure from the cover and help protect your pool walls by giving a buffer zone between the cover and the water.

It also helps to keep rain, snow, and leaves from collecting on the cover. You can even hook your chlorinator to an air pillow in the middle of your pool to keep it from sticking to the side and staining the plaster/vinyl. Otherwise, just leave your floating chlorinator out for the winter.

Either tie down your pool cover or use something heavy to keep it in place like water bags or blocks intended to keep covers in place and sealed off as tightly as possible.

I know, I know. We’re sad that pool season is coming to an end. But if you don’t procrastinate and take care of your pool NOW, it will be ready all the sooner come spring. Follow our pool closing checklist to make sure you don’t forget any vital steps!

Pool Closing Chemicals: Guide to Winter Chemicals

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