There’s nothing better than being able to take a dip on a hot summer’s day. But when the weather turns chilly, it’s time to learn how to winterize a pool. Weather-related damage, pollutants, and dirt can wreak havoc on your dormant backyard oasis during the colder months. Learn how to winterize an above ground pool or hire a local pool closing service to handle this task for you.
How to Winterize a Pool in 12 Steps
When temperatures dip, it’s time to put your pool in hibernation
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Difficulty
Saturday skill builder.
Time to complete
Cost
Make room—this DIY requires a lot of supplies!
What you'll need:
- Skimmer plate
- Pool air pillow
- Pool cover
- Leaf rake
- Skimmer net
- Pool brush
- Bucket
- Pool vacuum (optional)
- Pool testing kit
- Phosphate remover
- Algaecide
- Shock
- Winterizing pill
- Floater and sorb
- Stain and scale remover (optional)
- Baking soda (optional)
- Calcium chloride (optional)
Adjust Phosphate Levels One Week Prior
Phosphate acts as an all-you-can-eat buffet for algae, and you’ll need to carefully balance your phosphate levels so you don’t end up with a green pool come spring. About a week before you close your pool, add a phosphate remover. Sometimes this product is wrapped into an algaecide, so always check the labels. You don’t want to accidentally double up on products.
Instructions vary, but you can generally pour the recommended amount into the skimmer while the pump is running.
Remove and Clean Pool Accessories
When the day arrives to close down your pool for the season, start by removing and cleaning any accessories in your pool, such as ladders, skimmer baskets, cleaners, floats, solar blankets, and steps. Gently wash off any dirty accessories and let them dry before storing them away in a safe location.
Deep Clean Your Pool
Hopefully, you’ve kept on top of pool cleaning duties throughout the swimming season. That way, winterizing your above ground pool won’t be too arduous a task. You can add scale and stain remover a couple of weeks before you start the job.
Gently scrub the sides and base of the pool with a pool brush and get everything off the floor (use a pool vacuum if you have one).
Use a leaf brush or skimmer net and be meticulous about lifting debris from the water surface.
The cleaner you leave the pool, the less chance of algae building during the winter.
Add Stain and Scale Prevention Products
Stains and scale can build up on the walls of your pool while it’s not in use—and they’re a pain to remove once they latch on. To prevent this, add a stain and scale prevention product (though balancing your calcium levels should help a great deal).
Stain and scale inhibitors are included in most inground or above ground pool winterizing kits. Add the product per the manufacturer’s instructions. Typically, you’ll need to pour in the proper dose when your pump is running. The pump helps circulate it through the water.
Test and Adjust the Water Chemistry
Using your testing kit, check the pool water chemistry (chlorine, alkalinity, pH) and adjust as appropriate. You can use baking soda to raise the pH and alkalinity or calcium chloride to increase the calcium hardness. Aim for the following:
Alkalinity concentration between 80–120 parts-per-million (ppm)
pH level between 7.3–7.6
Calcium hardness between 175–225 ppm (for a vinyl or fiberglass liner)
Chlorine (if you use this for cleaning) between 1–3 ppm
Plumping for the higher end of the ranges means the chemical balance lasts better through the winter.
Add Shock and Algaecide
Shocking your pool sounds dramatic, but it's simply the name given to the process of adding a specific chlorine or non-chlorine chemical pool product to raise the free chlorine level. This helps get rid of pesky chloramines, bacteria, algae, and other contaminants that make your pool cloudy and unsanitary.
You should already be familiar with the process, as it's done regularly throughout the summer as part of ongoing pool maintenance. But it’s also an essential step in winterizing your above ground pool.
Always follow the manufacturer guidelines for application and dosage volumes. For a very dirty pool, you might have to shock it two or three times to maintain safe chlorine levels. If you're concerned about algal growth, you can also add an algaecide, but check whether it's safe to use this alongside your shock treatment.
Alternatively, lift the cover of your pool every few weeks during winter and if you see any signs of algae growth, add the algaecide then.
Clean Your Pool Filter
You want to kick off winter with a squeaky clean pool filter, especially if you’re storing your filter indoors. The method depends on the type.
Diatomaceous Earth (DE) Filters
Let your pump run for at least eight hours, then drain your filter. Remove the grids, and give them a thorough rinse with a garden hose. Once you’ve removed the excess DE, leave the valves open.
Cartridge Filters
Let your pump run for at least eight hours, then drain the filter. Remove the filter cartridge, and manually clean it with a hose. Leave the valves open, and store the cartridge indoors in a safe place.
Sand Filters
Sand filters are a bit more complicated. Make sure the filter’s multiport valve is set to “winterize.” After that, you’ll need to remove the drain plug and drain the filter completely. Some sand filters have a bleeder valve and a sight glass, which you’ll also need to remove. You can store these in the pump basket for the season.
Ideally, you’ll want to bring your sand filter indoors for the winter. This isn’t always feasible because sand is heavy. If you can’t lift the filter and plan to leave it outside, make sure you’ve removed the drain plug to prevent cracking.
Add Winterizing Chemicals
After your levels are balanced and you’ve shocked your pool, it’s time to add the final winterizing chemicals. If you’ve purchased a pool winterization kit, it will typically come with a product called a winter pill, winter floater, or winter sorb. These products float on top of the remaining water, releasing a number of chemicals that clarify water, inhibit stains and scale, and enhance helpful enzymes throughout the season. Add the products per the manufacturer’s instructions.
Turn off Your Pool Equipment
When you’ve cleaned your pool and added the right chemicals, it’s time to officially let it hibernate. Turn off your pool equipment—including everything from your pool heater and pump to pool lights and any other equipment. Shut off the main power breaker for your pool, and make sure to deactivate any timers you might have set during the swim season.
Protect Your Skimmer
An above ground pool skimmer hangs on the side of the pool, just submerged in the water. It pulls water through the basket, filtering off dirt and debris. If you invest in a winter skimmer plate, remove the hose, drain the skimmer, and fit the plate. This prevents freezing and cracking without you having to change the water levels.
Don’t want to invest in the skimmer plate? Lower the water levels using a hand siphon or pump to 4 to 6 inches below the skimmer. Just don’t drain your pool fully. This dries out the vinyl liner, decreasing its lifespan.
Drain and Store or Cover Equipment
Water in the lines, pumps, or filters continually freezes and thaws during a hard winter. This expansion can damage the equipment. To avoid this and unsanitary mold growth, drain away the water, thoroughly dry the items, and then store them in a dry spot. In particular, you’ll want to remove and store your:
Pump
Chlorinator
Hoses
Drain plugs and/or caps
Filters or filter cartridges
Whatever equipment you can’t store, you’ll need to cover. You can purchase a pool heater cover to protect your heat pump or pool heater. It’s also a good idea to use mothballs and mint sachets to keep pests like mice out of the pool heater when it’s not in use.
Lower Water Level to Install an Air Pillow
When ice or snow builds up on top of your pool cover, it presses against the water and gets stuck when it freezes over. Using an air pillow in the middle of the water surface, or a few if you have a large pool, prevents ice from expanding outwards. You’re less likely to have ice creating damaging pressure on the pool walls.
Before placing an air pillow on your pool, you’ll need to lower the water levels. This process could take one or two days, depending on the amount of water you need to remove.
Cover the Pool
You don't want your pool to fill up with leaf litter and other debris over the winter, so fitting a snug, secure cover is a must.
A well-fitting pool cover (steer clear of flappy tarps) stays on regardless of the weather, so don't weigh it down with something like a brick. This is more likely to damage the cover and possibly even the pool. After a big dump of snow, take the time to clear any piles off the cover.
How to Winterize an Above-Ground Pool
While there are many differences between in-ground and above-ground pools, the steps to winterize them are pretty similar. Both require cleaning, adjusting the pool's chemistry, lowering the water level, prepping components for storage, closing the filter system, and covering the pool.
Here are some key difference to note when closing an above-ground pool:
Don’t need to drain all the water: If you use skimmer covers, you don’t need to drain all the water from the pool. Consult a local pool service to determine the best water level for the winter.
Use nylon brush for cleaning: When scrubbing the scale before closing your pool, use a nylon brush instead of pumice stone for above-ground pools.
Install an above-ground pool cover: Be sure to purchase and install a pool cover made specifically for above-ground pools that fits its size appropriately.
DIY vs. Hiring a Pro
Although winterizing your pool doesn't involve anything too technical, there are multiple steps. Plus, if you miss a step, there may be some disappointment come summer if the pool suffers from freeze damage or algae buildup.
If you’re worried about balancing the water chemistry or you’d rather free up an afternoon, hiring a professional pool closer near you offers convenience and peace of mind. They know how to close an above ground pool without any fuss, so you can have an easy opening come summer.
Expect to pay $150 to $300, which includes the cost of the chemicals. To budget for swimming pool maintenance costs, it’s helpful to know that pros typically charge $75 to $100 per hour. You’ll still have to invest in cleaning and balancing supplies if you do it yourself, but you could save $75 to $200 (or more if you bulk buy some chemicals).
Frequently Asked Questions
You should winterize your above ground pool in the early fall, when temperatures start dropping. If you’re lucky enough to live in a region with year-round balmy temperatures, you won't have to worry about winterization at any particular time of year. Keep an eye on the forecast—you want to take action before the temperatures start dropping below 65 degrees Fahrenheit.
There are a few differences when it comes to winterizing above- vs. inground pools. Above ground pool winterization usually involves less hassle, time, and expense than the process for winterizing an inground pool. All the lines on an above ground pool are easy to access, making draining easier. Plus, above ground pools are typically smaller, meaning cleaning is quicker, and chemicals cost less.
When you’re winterizing your pool, you need to drain some of the water to prevent cracking and warping from ice. Nonetheless, you should never drain all of the water. Ideally, you’ll lower the water level to anywhere from four to six inches below the skimmer. This will protect the structural integrity of the walls, help prevent your pool liner from warping, and reduce damage from debris.
Winterizing your above ground pool is essential if you live in a colder climate. When water freezes, it expands. This can damage and crack pool equipment like your pipes, pumps, hoses, and liner. In some extreme cases, it can warp the pool walls and cause your pool to collapse.
Beyond that, winterizing your pool prevents the buildup of algae and bacteria, reduces the amount of scale and staining, and keeps out debris. This way, things are easier to get back up and running when it’s finally swim season.