How To Close Your Pool For Winter

Rachel BurrisSeptember 09, 2019

As the summer comes to a close, it can be hard to muster the energy to close your pool. After all, throwing that winter cover over your pool signals the end of lazy summer days and the beginning of a whole new year of responsibilities. While you may be inclined to leave the pool chores to next summer, the job will be a much bigger headache if you try to put it off.

As a pool owner, you know how much junk accumulates in your pool. Every time a summer breeze blows across your backyard, leaves, insects and other debris find a way into your oasis and you’re the one who has to clean it out.

Now, imagine how much more the strong gusts of fall can carry. If you leave your pool uncovered after the temperature drops, you’re letting all of that junk slowly rot at the bottom of your pool for months. Failing to clean your pool out can throw off its water chemistry and cause the skimmer to clog. Ultimately, choosing not to close your pool will cost you more money and time when it comes to making your pool swimmable next summer.

So instead of dragging your feet, read through this article and follow the steps necessary to make swimming just as enjoyable next summer as it was this summer.

(Happen upon this page by accident? If you don’t have a pool but want one, we can help you find a pool that’s right for you.)

When You Should Close Your Pool

The cooler the temperature, the easier it is to clean, test and balance the water in your pool. As a result, it’s recommended that you wait until the weather is consistently below 65 °F (18 °C) to start prepping your pool for winter. Waiting until the temperature drops will ensure your water stays cleaner because algae don’t grow as rapidly when it gets cooler out.

Unfortunately, warmer weather comes at a price. If the weather in your area stays warmer longer, you may have to continue testing and balancing the water throughout the off-season to ensure your pool remains clean. That said, you won’t have to worry about taking freezing precautions so you’d be able to leave your pool pump running throughout the year.

What Supplies You Should Have On Hand

There’s a long list of supplies you need to close your pool, but you should have most of them already as these supplies are also necessary for keeping your pool swimmable during the summer. Check to make sure you have the following items:

  • Tool kit (to remove pool accessories)
  • Pool net, brush, vacuum and telescoping pole (to remove debris)
  • Algae brush (if there’s a noticeable presence of algae in your pool)
  • Water test kit or test strips (to check the chemistry levels)

Depending on the levels, you may need:

  • pH increaser
  • pH decreaser
  • Alkalinity increaser
  • Muriatic acid
  • Calcium hardness decreaser
  • Cyanuric acid (to stabilize chlorine molecules)
  • Pool Sanitizer (such as chlorine, bromine or salt)
  • Algaecide (to prevent algae growth)
  • Chlorine or chlorine-free shock (to destroy contaminates)
  • Metal sequestrant (to prevent discoloration of pool water)
  • Pool antifreeze (to prevent pipes from freezing and bursting)
  • Pool winterizing kit (to buy fewer chemicals a la carte and ensure your pool is clean and balanced throughout the off-season)
  • Air compressor with fittings (to blow out the pipes)
  • Winter pool cover or safety cover (to protect water against debris or prevent accidental drownings)
  • Water tubes or weights (to keep your pool cover in place; unnecessary for above-ground pools)
  • Rubber pool plugs (to prevent water from entering and freezing pipes)
  • Gizzmo skimmer guards (to prevent skimmers from freezing and cracking)

Some of the supplies needed may vary based on your location and pool maintenance habits, so be sure to ask someone at the pool store if you have any questions.

Steps For Closing Your Pool

Get Cleaning

The first step to closing your pool is cleaning it. If you don’t clean your pool with care, all subsequent steps will be for naught.

Begin by using a pool net to skim any debris floating on the surface. Once you’re done, it’s time to scrub the walls and floors of your pool. Take your pool brush and connect it to your telescoping pole so you can get at those hard-to-reach places. Don’t forget to clean the skimmer by pulling out the baskets and removing anything that collected inside.

Worried about algae? If you find that your water has a green, yellow or blue-black tint to it, you definitely have an algae problem. Even if the water color seems right, double-check that there’s no sign of discolored residue anywhere in your pool. If you find any, make sure to go to town on each area with an algae brush.

After you dredge up all sediment and algae, you should vacuum it out manually. All of the pool’s surfaces will need to be vacuumed, especially those nooks and crannies that usually get overlooked. Those areas are algae havens, so make sure you give them a little extra attention.

Test And Balance The Water Chemistry

To ensure that your pool is swimmable next summer, you’re going to want to use your water test kit to check that the water is balanced. When testing the water balance, you’re going to be on the lookout for the chlorine, pH, alkalinity and calcium levels. Take out a test strip, dip it into the pool water and compare the results to the chart included with your kit.

You want your chlorine level to be between 1 – 3 ppm (parts per million). Beware of chlorine levels above 5 ppm as such high levels can prevent other chemicals from working.

Your pH level should be between 7.2 – 7.6. If the pH level is below this range, your water will be too acidic and corrode your pool. If it’s above this range, your water will cause algae to grow.

Your alkalinity, which ensures that the chlorine is working and your water remains crystal clear, should be in the range of 80 – 120 ppm while your calcium hardness should be around 200 – 400 ppm. If your calcium levels are too low the water can actually eat away at the plaster, liner, grout, metal and concrete in and around your pool. If the calcium is too high, the water can take on a cloudy appearance and irritate swimmers’ eyes and skin.

Once you’ve tested the water chemistry, you may need to add chemicals to balance the levels. This stage is where pH increaser, pH decreaser, alkalinity increaser, muriatic acid (to decrease alkalinity) and calcium hardness increaser may come in. Just make sure your pump is running whenever you add chemicals to your pool.

Shock The Pool

A few days before you actually throw the cover over your pool, you should shock it. Using pool shock will kill any bacteria that may be left floating around in your pool. When you shock your pool, you’re adding high levels of chlorine to it. Since the sun can break down chlorine and diminish the effectiveness of shock, you should always wait until the evening to shock your pool. When you do, make sure to read the manufacturer’s instructions clearly to avoid any missteps. You should keep your pump going all night so the chlorine goes through the circulation system and is distributed throughout the pool.

Add Winterizing Chemicals To The Pool

Once you’ve shocked your pool, you may feel ready to pull out your pool winterizing kit. But slow down. You’ve just pumped your pool full of chlorine, so you need to wait until the chlorine level drops back down to 3 ppm before adding any other chemicals. If you don’t wait, the high chlorine levels will likely reduce the effectiveness of subsequent chemicals.

But as soon as the chlorine level has normalized you can start adding other winterizing chemicals. Buying a winterizing kit can make your life a little easier and your pool costs a bit lower since you won’t have to buy each chemical individually. But if you’d rather buy these chemicals a la carte, be sure not to leave out any of the important ones.

If you want to be sure that your pool stays clean and is swimmable as soon as the warm weather returns, you’re going to want to add algaecide. Algaecide will kill remaining algae and prevent more from growing.

Metal sequestrant is another chemical you should put in your pool before closing, especially if you already know there’s a high level of metals present in your water. If you fill your pool with well water, you should definitely be using metal sequestrant before closing. Metal sequestrant prevents the discoloration of pool water in addition to the rusting and staining of pool surfaces by blocking metals and minerals from binding to the surfaces of the pool.

Many pool winterizing kits also come with a WinterPill. Unlike other treatments that subside quickly, WinterPills contain enzymes, sanitizers and clarifiers that are released gradually over time so they’ll attack contaminants in your pool well into the winter.

Backwash The Filter

When closing your pool, you have to go beyond what the eye can see. Remember, the key to a clean pool is a clean filter. To flush out all the debris in your filter you’ll need to backwash it, which means reversing the direction that water flows through the filter.

To do so, check that your heater is off. Then, shut off the filter and turn the valve to Backwash. Your system may send waste directly to a drain. If not, you’ll have to connect a hose to the system and make sure the hose leads to a safe place to dispose of the waste.

Next, you’ll need to turn the filter back on and allow it to run for a few minutes. Continue letting it run until you see that the water flowing through the sight glass is clear.

Once it is, turn off the filter again and set the valve to Rinse. Turn the filter back on, let it run for just under a minute and then turn it off again.

Turn the multiport valve back to Filter. Pool filters don’t come cheap, so it’s important you complete this step with care as it’ll extend the life of your filter.

Lower The Water Level

Lowering the water level is unnecessary if you live in a warmer, drier climate. But for you brave souls who have to bundle up during the winter, make sure you don’t skip it. Failing to lower it in colder climates can cause ice damage to your plumbing lines.

To prevent your pipes from freezing (or worse, bursting), you’ll want to drain your pool until the water is a few inches below your pool’s skimmer.

To lower the water, shut off the filter and turn the multiport valve to Waste. If you needed a hose to backwash your filter, you’ll be needing it again to drain the water. Hook it up and make sure it drains into a safe place.

Ideally, you want the main drain to be the only one open; if you can close your skimmer valves, you should do so. Next, turn on the filter and watch the water level drop. Once the water level is a few inches below the skimmer, turn the filter off. You can then prepare and store the filter elements for the winter.

Clear The Lines

In colder climates, it’s necessary to blow out the pool plumbing lines because any water left in the lines can freeze, leading your pipes to burst. If you don’t experience freezing temperatures in your area, this step isn’t necessary to follow.

To complete this step and safely prepare your pool equipment for winter, you’ll need to ensure that you’re able to eliminate all traces of water from the pump, lines and filter. If you’re concerned about your ability to do this perfectly, you should consider calling in an expert. There’s no shame in asking for help, especially at this stage. The last thing you want is to be forced to spend a fortune because you accidentally left some water in your lines or damaged the plumbing in the process of blowing air through it. If you decide to proceed independently, do so with caution!

Begin by removing the return jet fittings and skimmer baskets. Go to the filter system and take the drain plug out of the pump. Grab your air compressor and use the fitting to connect it to the drain port. You need to prevent air from coming into the filter, so set the multiport valve and the main drain valve to Closed. Because you’re going to be blowing the water out through the skimmer, you’ll also need to close one of the skimmer valves if you have two skimmers.

With your air compressor set low, blow the water out through the skimmer. Someone should help you by vacuuming the excess water out of the skimmer. Look out for bubbles around the skimmer intake. When you see them, insert your Gizzmo skimmer guard into the skimmer intake. Vacuum whatever water remains in the skimmer and go over to the filter to close the skimmer valve. You’ll then repeat those same steps to clear the line of the other skimmer.

Once you’ve blown out the skimmers and closed the valves you want to force the air through the main drain, so open the valve. Don’t turn the main drain valve off until you see a current of bubbles coming from the bottom of the pool.

Next, you’ll have to blow out the return lines. Head to the filter and turn the multiport valve to Recirculate. When set to Recirculate, air will bypass the filter and go through the return lines. Keep an eye on the return lines. When you see bubbles coming from the side of the pool, insert rubber plugs in the return lines.

Remove the Gizzmo skimmer guards from the skimmers to add pool-grade antifreeze. Although it’s not always necessary, adding antifreeze will protect your pipes just in case there’s a bit of water left in them. If there’s water left, leaving the skimmer valves open will also help protect your pipes as it’ll leave room for expansion in case the water freezes. Then, turn the multiport valve to Winter.

Disassemble And Store Filter And Pool Accessories

Unplug everything connected the filter system and dismantle the sight glass and pressure gauge. If you’re worried about misplacing the parts, store them in the strainer located inside the pump.

You can choose to cover the filter and pump to ensure it’s protected from the elements. But you don’t want to damage the pump by securing the cover too tightly. You can tie a rope around it, but do so loosely.

Next, take down your ladders, rails and any other pool accessories so they don’t rust or deteriorate from the winterizing chemicals in your pool. Clean them thoroughly before storing them. It’s also a good idea to clean out your skimmer baskets one last time. You don’t want anything decomposing or growing in there over the winter.

Put The Cover On Your Pool

It’s important that you remove all accessories from your pool before putting the cover on because you want the cover to fit snugly. Improperly secured covers can cause contaminants to sneak in during the winter.

When buying a cover, you want to choose between a winter cover and a safety cover. A winter cover will protect your pool against the elements and ensure the pool stays clean throughout the year. If you choose a winter cover, make sure to get water tubes or pool cover weights to keep your pool sealed and your cover in place.

Though it’s the more expensive option, a safety cover is a great idea as it’ll safeguard against tragic accidents such as drowning. If you buy a safety cover, you won’t need to worry about buying tubes or weights either.

Regardless of the type of cover you get, keep an eye on it throughout the year. You want to make sure it stays clean and isn’t weighed down by water or snow. You should periodically sweep it off with a broom; you can even get one that has a squeegee attachment to assist in getting rid of any water that collected on top of the cover.

How Do You Close An Above-Ground Pool?

If you have an above-ground pool, the process of closing it is very similar to that of an inground pool. The only differences occur in the last few steps: winterizing your skimmer, filter and pump and then covering your pool.

In order to preserve your skimmer, take out the basket and put a winter skimmer cover on it. The cover is actually a plate that goes over and seals the entire skimmer. This plate will protect your pool from changes in weather and prevent you from having to drain too much of your pool. Take the hose off your skimmer, allow it to drain and cover the skimmer with the plate.

For an above-ground pool, the best way to protect your hardware is to store it indoors for the winter. To begin, dismantle and drain the pump. Make sure you undo all drain plugs and hoses. It’s a good idea to store the plugs in the basket of the pump so you know where to find them next year. Next, remove the drain plugs and open the valves of your filter. Dry your pump, filter, chlorinator and heater, and then store them in a cool, dry place.

Since you’ve covered your skimmer with a winter cover, you don’t need to drain your above-ground pool. If you do drain it, make sure the water stays above the return lines. When winterizing it’s crucial you don’t drain your entire pool as it’ll age your pool by drying out its liner.

Before you throw the cover on your pool, it’s smart to install a pool air pillow (or ice compensator). These pillows ensure that the walls and cover of your pool aren’t beaten up by snow or ice. When using an air pillow, it’s helpful to blow it up only halfway so it doesn’t pop when the snow starts to pile up. After you inflate the pillow, put it in the middle of the pool and use a light rope to keep it there; some pillows come with accessories that’ll secure the pillow.

Once you’ve centered the pillow, all that’s left is the pool cover. Put the cover over your pool and tie it down with a cable and winch or winter cover clips. Your work is then done, though you’ll want to keep an eye on your cover throughout the winter.

Closing your pool for the winter can be a confusing process, and while this article is here to help, you may find you could use a bit more assistance. If you’re confused about any of the above steps, call your local pool company. They’ll be happy to help and answer any questions you have that are specific to your location and pool. Either way, you can be sure that when next summer rolls around you’ll have a lovely, clean pool to splash around in. In the meantime, check out some fun pool party ideas that’ll help you take your mind off impending winter blues.

Rachel Burris

Rachel Burris is a writer covering topics of interest to present and future homeowners, as well as industry insiders. Prior to joining Rocket Companies, she worked as an English teacher for the New York City Department of Education and a licensed real estate agent for Brown Harris Stevens. She holds a bachelor's degree in creative writing from Bucknell University, a postbaccalaureate certificate in psychology from Columbia University and a master's degree in English education from Teachers College, Columbia University.