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National Pool Closing Day

Opening your pool for the season is often a great event for you and your family. But just as opening your pool is important, closing it is as well. To help remind everyone to properly prepare their pool for the off-season, we recognize National Pool Closing Day, which falls on the third Saturday in September.

Why You Should Close Your Pool

Closing your pool during the off-season is important because if you don’t, you’ll have significant work to make it swimmable again when spring/summer rolls around. This is partly because leaving a pool open year-round would mean that plenty of debris has made its way into your pool — settling into the bottom, clogging up your skimmer — and most importantly, your pool’s water chemistry will become extremely unbalanced.

To put things in perspective, if you fail to properly close your pool, opening it will be more costly to set your pool right up again. This can all be avoided if the proper measurements are taken to close your pool before the winter months arrive. Seems like an obvious choice to us.

BONUS TIP: Need help closing your pool? Call or stop by your local Leslie's store to ask about our pool closing services.

How To Properly Close Your Pool

1. Clean up dirt and debris in your pool

Leslie's Pool Cleaning

Scrub your pool walls and floors with a pool brush attached to a telescoping pole; ensure that you're getting into the nooks and crannies to the best of your ability.

Brushing your pool will kick up any sediment hanging around, as well as disturb the beginnings of any algae spores. Manually vacuum all the contaminants you kicked up while brushing or entrust your automatic pool cleaner to do the job for you, if you own one.

2. Check your water’s chemistry, and add winterizing chemicals

Leslie's Pool Shock

First and foremost, you must check the water chemistry in your pool. Depending on the result, balance the pH, Total Alkalinity, and Calcium Hardness levels. Did you know that balancing the chemicals in your pool water before closing actually protects it from scale building that can occur over the winter months?

Once the water is properly balanced, we also suggest shocking your pool and adding algae remover. This will kill any remaining bacteria and prevent algae from growing in the water.

It’s advised that you leave your pool alone for a full 24 hours after balancing the chemicals before you go to the next step.

BONUS TIP: Looking for an easy solution to winterizing your pool? Leslie's Pool Closing Kits take the guesswork out of which chemicals your pool needs. Each kit includes Fresh 'N Clear chlorine-free pool shock, a bottle of Algae Control, and stain and scale prevention products. All you have to do is select the right kit according to the size of your pool.

3. Turn off equipment, and lower the pool water level

Draining a Pool

Before removing water from the pool on pool closing day, turn off the power to your pool equipment. Using a submersible pump, lower the water level in your pool. It’s best if you lower the water at least 2 inches below the lowest return line. Lowering the water level properly when you’re closing the pool helps prevent freeze damage, and in some instances, overflow. If you live in an area where snow isn’t an issue, but rain is, it’s a good idea to check the water level occasionally while the pool is closed.

4. Drain pool equipment, and winterize plumbing

VS Pool Pumps

To prevent any damage from freezing, it’s best to drain and clean all pumps, filters, heaters, cleaners, and other equipment for the winter. If your equipment or plumbing has leftover water sitting inside, you run the risk of the water freezing, expanding, and cracking your equipment when the temperature drops. Remove all drain plugs from equipment, and store them in the pump basket for safekeeping. If possible, equipment should be stored indoors or under cover for the winter.

To protect your plumbing, clear out the lines with a blower, and plug the returns with winter plugs. If you don't have a blower, use winter plugs to plug the lines, then add swimming pool antifreeze according to label instructions. Pool antifreeze is also good to use as a safeguard, even if you used a blower to purge the lines, just in case a plug fails. Finally, add a Gizzmo or skimmer plug in the skimmer to protect against freeze expansion.

5. Add a winter cover

Complete Pool Closing

Last but not least, install a winter cover for your pool. Before getting started, remove all ladders, hoses, or anything else that's in or around the pool. If you already own a winter cover or a safety cover, ensure that it fits correctly and inspect it for holes or damage in the surface material. You don't want there to be spots where debris can get through to the water. It’s also suggested that water bags be used to secure your inground pool winter cover, or use an air pillow with either wall bags or a cable and winch to secure an above ground pool winter cover. If using a safety cover, ensure that the straps and anchors are in good repair. This maximizes the security of your pool during those harsh winter months.


In the weeks leading up to National Pool Closing Day, check to make sure you have all the pool closing supplies you'll need to make the process go smoothly. Have all your water balancing supplies, pool closing chemicals, and winter accessories ready to go.

If you're re-using your winter cover from last year, take a look at it to make sure it's still in good condition. If it's not, make plans to purchase a new one before you start the pool closing process. As always, feel free to stop by or call your local Leslie's store for help with all your pool closing questions. You can also check out the Pool Closing category of our blog for more helpful tips and tricks.

A properly closed and winterized pool will be significantly easier to open in the spring, and we're here to help!

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