How to Winterize an Above Ground Pool (Complete Guide)

Above-ground pools can freeze and become permanently damaged during the winter. If you don’t treat your pool correctly, the equipment will crack from the frozen water. Furthermore, the liner can crack or get too dry. Winterizing your swimming pool is easy and can be done in less than a few hours.

To winterize an above-ground pool, follow these steps:

• Remove debris
• Test and adjust the chemicals
• Shock the pool
• Use a clarifier
• Partially drain the pool
• Install pool pillows
• Add a winter cover
• Run the pump during the coldest hours

In this post, I’ll dive into the step-by-step process of winterizing an above-ground swimming pool. I’ll also answer the most common questions about dealing with an above-ground pool during the coldest months of the year.

Remove Debris From the Pool

Trapped debris will eventually cause algae blooms. If you close the pool for the winter and there’s a lot of debris in the water, it’ll stain and corrode. Long-term algae exposure is unhealthy for the pool. It can also damage the winter cover and water pillows. It’s important to remove as much debris as possible before winterizing.

Try these tips to remove as much debris as possible:

• Run the vacuum one last time. Pool vacuums remove almost all of the fine debris on the bottom of your swimming pool. You can also choose leaf vacuums that get rid of leaves, pine needles, and other large debris. I suggest a long vacuuming session to thoroughly clean the pool before adding chemicals.
• Use a skimmer net to remove all of the floating debris. Skimmer nets are inexpensive. However, they’re a staple for almost every swimming pool. You can choose a deep or shallow net, depending on the size of the debris in the water. Deep nets are good for large debris, whereas small nets pick up tiny leaves and bugs.
• Brush the edges of the pool to get rid of algae and scale buildup. Use a soft bristle brush for vinyl or fiberglass and a stiff bristle brush for gunite and pebble pools. You can use a pumice stone or wire pool brush around the tile line to remove calcium deposits. Remember to work in one direction only.
• Clean the filter to collect additional debris. Your filter slowly fills with the debris in the pool. Cleaning or backwashing the old debris out of the filter will open it for additional contaminants in the water. You might need to clean the filter numerous times while deep cleaning an above-ground pool before winterizing it.
• Repeat this process once you’re done adjusting the chemicals. The initial cleaning process will take much longer than the second one. However, I always recommend pool owners go through these steps after adjusting the pool’s chemicals because it winterizes the pool in the cleanest way possible.

Everything in your swimming pool will affect the chemistry. Natural debris can be quite acidic, which means it needs to be removed before testing, adjusting, and covering the pool. Removing the debris also helps the chlorine circulate to prevent algae blooms.

Test and Adjust the Pool Chemicals

Testing and changing the chemicals will keep your pool in good shape for the winter. It’s important to ensure every chemical is in the recommended range. For example, an acidic swimming pool will corrode through the equipment, whereas a high-pH pool will develop stains and scales.

Here are the primary above-ground pool chemicals to check:

• Chlorine: Keep your pool’s chlorine between 2ppm to 5ppm. I recommend spiking the chlorine to 5ppm before winterizing the water. Not only does it prevent algae from blooming, but it also maintains the chlorine for a couple of weeks with a high-end winter cover. You can use liquid chlorine or granular chlorine to get the job done.
• Algaecides: Copper-based algaecides naturally prevent algae from growing. They’re some of the most important chemicals for winterizing a pool, regardless of if it’s above-ground or inground. You can also use a phosphate remover to keep algae’s food source out of the pool.
• Alkalinity and pH: Keep the alkalinity between 80ppm to 120ppm and the pH between 7.2 to 7.8. I suggest getting both chemicals as close to the center of their ranges as possible. Use soda ash or baking soda to increase them and dry acid or muriatic acid to reduce them. Using a cover will prevent significant pH adjustments.
• Calcium hardness: Never let the pool’s calcium levels get above 400ppm. Your pool’s calcium prevents corrosion, but too much of it results in stains and buildup. While calcium doesn’t cling to vinyl too well, it can leave deposits in the equipment and around the edges of the swimming pool.
• Phosphates: Phosphates are algae’s primary food source. They come from anything natural that gets in the water. Try Natural Chemistry’s Phosfree to remove the phosphates from the water before winterizing the pool. One bottle will last a couple of years, depending on the size of your above-ground pool.

Adjusting these chemicals will put your pool in the best place to stay clean and clear throughout the winter. With the proper cover, you shouldn’t have to change the water’s chemistry too often. You’ll also prevent stains, corrosion, buildup, and other issues caused by pool chemical imbalances.

Shock the Pool to Maintain the Chlorine

Shocking the pool will spike the chlorine quite a bit. High chlorine levels prevent algae. A winter cover will preserve the chlorine for a couple of weeks. It prevents the chemicals from evaporating. However, it’s important to shock your above-ground swimming pool every few weeks during the winter months.

Try In the Swim’s Calcium Hypochlorite Granules. This chlorine shock has 68% free available chlorine, which is as high as it gets for above-ground swimming pools. Each 50-pound bucket is more than enough shock to last for several years. You can use this shock in above-ground pools, in-ground pools, and chlorinated spas.

Before you shock the pool, remember these three tips:

1. Never use harsh granule shock in an above-ground swimming pool. I recommend keeping your pool shock below 70% free available chlorine. Extreme shocks are designed for inground pools. They can damage the vinyl liner and cause permanent damage. If you’re worried about it, opt for liquid chlorine since it’s much less harsh.
2. Always run the pool pump for several hours after adding pool shock. This is undoubtedly the longest part of the winterizing process. Thankfully, you can brush and vacuum the pool while the shock is in the water. In fact, this process aids the pump’s circulation, encouraging thorough chlorination.
3. Never pour any type of chlorine into the equipment. Many pool owners make the mistake of dumping liquid or granular shock into the skimmer basket. This mistake will destroy the basket, pump, and plumbing. Instead, pour the shock around the edge of the pool while the water is circulating.

Pool shock is likely the most important factor when you’re winterizing a swimming pool. It prevents algae, especially when paired with the right kind of algaecide. Contrary to popular belief, you have to chlorinate your swimming pool every couple of weeks during the winter. The cover doesn’t prevent algae growth completely.

Use a Water Clarifier

Water clarifiers remove dead algae and other debris from the swimming pool. They sit in the filter, preventing fine contaminants from getting through. Some water clarifiers clump everything and drop them to the bottom of the pool. Make sure you clean the filter after using a clarifier to prevent the filter from clogging.

I always suggest customers get a micron density water clarifier. These clarifiers are the best because they filter everything going through the plumbing. While other water clarifiers clump the debris, you have to manually remove the clumps. With a traditional water clarifier, all you have to do is backwash and rinse the filter (or spray the cartridges, depending on your filter).

If you’re looking for a water clarifier, try the Robarb Super Blue Pool Clarifier. One capful treats 5,000 gallons, which is the average size of an above-ground swimming pool. Dump the clarifier into the skimmer basket, turn on the pump, and watch as the water gets much clearer. Rinse the filter with hose water once the PSI gets over 25 on the filter’s pressure meter.

Those using water clarifiers should focus on these concerns:

• I suggest cleaning the filter before and after using them. The cleaning process helps the clarifier cling to the filter media if there’s not too much debris. You’ll be able to remove several times more contaminants from the water by getting the pressure between 10 PSI to 15 PSI.
• Water clarifiers can be dumped directly into the skimmer basket or pump basket. Unlike most chemicals, you shouldn’t dump your clarifier around the edge of the pool (unless directed by the manufacturer). These clarifiers need to go directly into the filter rather than around the swimming pool.
• Check the label to know if you can use pool shock with your water clarifier. Some pool clarifiers can’t be used in the water if there’s too much chlorine. I always recommend testing the chlorine and checking the manufacturer’s guidelines to know if there’s an issue. The last thing you need is to dump your clarifier down the drain.

Water clarifiers are an important part of the winterizing process. However, they might be unnecessary if your pool is clean and clear. It’s best never to cover a pool if it’s cloudy or dirty. These clarifiers make a huge difference by preventing algae from coming back and keeping your water in good condition.

Drain the Water to the Correct Height

I suggest draining your pool six inches below the top of the skimmer. Partially draining the pool prevents the water from freezing. It also stops the water from making contact with the winter cover, which stops frost from forming. Never let the water get below the skimmer’s inlet, though. When the water is too low, air will get into the plumbing.

Your pool water shouldn’t touch the winter cover. It also shouldn’t get too low. If it’s below the highest inlet (which is usually in the skimmer basket), your pool will get a ton of air in the plumbing. Instead, drain the water a few inches lower than normal without letting it get too low. You’ll notice a massive difference when you reopen the pool in the spring.

Another reason you should drain the pool a bit is to make room for the pool pillows. The pillows are often a few inches high. This means they’ll be too far above the edge of the pool if you don’t drain some of the water. Failure to drain the water can render the pool pillows useless, which wastes your time and hard-earned money.

Draining your above-ground pool is quite simple. Try one of these three methods:

1. Remove the pump’s drain plug. All pool pumps have a drain plug that lets you get rid of most of the water in the pump. However, since above-ground pools have gravity working in their favor, you can remove the pump’s drain plug and get rid of as much water in the pool as necessary.
2. Look for a drain cap on the side of the pool. Many above-ground pools have drains around the lower edges. You can also remove the tubes going to the inlets and outlets. These tubes quickly drain the pool, so it’s best to have someone keeping an eye on the water level while you drain the water.
3. Use a sump pump. The Superior Pump 1/4HP Utility Pump goes into your pool and removes water with a garden hose. Turn it on and wait until the water is as low as you want it to be, then flick off the motor, and you’ll be good to go. You can also use this lightweight pump to remove water on top of your pool cover from rain and snow.

Install Pool Pillows Around the Edges

Pool pillows hold the winter cover over the water. They prevent the water from contacting the cover, which could freeze the cover and cause deterioration. These pillows stop rain, snow, and hail from pushing the cover into the water. Always place a pillow in the center, but you could improve the setup by lining the edges with more pillows.

It’s hard to beat the In the Swim Pool Pillow. This 4’ x 4’ pillow sits in the center of your pool and pushes water off the edges. You can place several of them around the edge of the pool or rely on one in the center. Those with rectangular above-ground pools might need two of these inflatable, durable pools (depending on the length).

The pillow should be the last thing you add before the winter cover. These pillows float around like a raft, so you might need someone to hold them while you install the cover. You can also use a telescoping pole to hold the pillow. The pillow needs to be as centered as possible for the best results; otherwise, it might sag and push the water to the middle of the cover.

If you don’t want to use a pool pillow, you can improvise by stacking a few rafts on top of each other and placing them in the center under the winter cover. This setup isn’t as effective since it doesn’t have equal balance, but it’s better than nothing.

Place a Winter Cover Over the Swimming Pool

Adding a winter cover is one of the best ways to close a swimming pool for the season. Winter covers are more durable than solar covers. Furthermore, they wrap around the edges to keep 100% of debris out of the water. Most winter covers are designed to withstand direct sunlight, rain, snow, and so on.

Winter covers come in all shapes and sizes. Most above-ground winter covers are designed specifically for the make and model. I recommend contacting the manufacturer and finding out which winter cover they suggest using. Many manufacturers require custom designs for their above-ground pools. The last thing you want is to have a cover that can’t cover the edges.

Here are three things you should know about putting a winter cover on an above-ground pool:

1. Always make sure the winter cover goes a few inches or feet beyond the edge of the pool to keep all of the debris off of the water.
2. You can’t replace a winter cover with a solar cover because they’re made with different materials, dimensions, and structural details.
3. Consider getting a winter cover with a drawstring, so you can tighten it as much as possible.

Run the Pump at the Coldest Time of Day

Running the pump will prevent the water from freezing. Frozen pipes will crack and destroy the equipment. Make sure you run the pump at the slowest speed possible. If you have a variable-speed pump, you can run it all day at 350 RPMs. Run your pool pump for at least four hours daily during the winter.

If you live in an area that doesn’t dip below freezing, you can stick to your regular pump schedule. For example, people living in a climate that doesn’t get colder than 50 degrees Fahrenheit in the winter can get away with running their pumps for five hours each day. Remember, the general rule of thumb is one hour per ten degrees.

Unfortunately, some pool pumps are quite noisy. Most single-speed pumps are significantly louder than variable-speed pumps. You could run your pool pump for a couple of hours before bed, then a couple of hours after waking up to prevent the water from freezing. Keep in mind that you don’t have to run the pump if you store a storable above-ground pool.

Do You Need to Drain an Above-Ground Pool During Winter?

You need to partially drain an above-ground pool during winter. You can drain the pool about four to six inches below the top of the skimmer to prevent the water from freezing. Your pool is much more likely to freeze if it’s too full. Storable swimming pools can be completely drained and stored during the winter.

Keep these suggestions in mind:

• Storable pools don’t need to be stored. You can leave your Intex pool up all winter, but some people prefer to store theirs. Most Intex pools are storable, which means they can be drained, dried, and kept in a storage container. Always keep your storable pools in a dry, room temperature location to prevent cracks and mold.
• Never drain an above-ground pool below the highest inlet if you intend to keep it up. If the water level is too low, air bubbles will get into the system. Air in the plumbing damages all of the equipment. If this happens, fill the water above the highest inlet and open the filter’s air relief valve until water comes out.
• Check with the manufacturer if they have specific winter draining instructions. Some pool companies have unique storage and winterizing details. While my instructions work for almost every above-ground pool, it always helps to find out what you should do with specific equipment and liner adjustments.
• Always remove your pool vacuum during the winter months. Pool vacuums can freeze. They have tiny moving parts, all of which can crack if they get too cold. The hoses can also freeze, causing plumbing issues. Air bubbles will get into the plumbing once the ice thaws, damaging your pool’s equipment.
• Dry your storable above-ground pool before storing it (if you drain the water). A small amount of moisture can cause mold and mildew. These unwanted growths will discolor and damage your above-ground pool’s vinyl liner. Always let the pool dry before placing it in an airtight container for the winter.

Draining your above-ground pool during the winter can be advantageous. Not only will you prevent unwanted freezing, but you’ll also save money on your water bill. However, I recommend never running your pump at its highest speed since it can ripple the water and invite air bubbles. Remember to top off the pool if it gets too low.

How to Keep Your Above-Ground Pool From Freezing

To keep your above-ground pool from freezing, try these methods:

1. Run your pump when the pool is as cold as it gets. The best time to run your pool pump is whenever it’s cold enough to freeze the pipes. Moving water is slightly warmer, and the cells move, which prevents them from freezing too quickly. Your pool shouldn’t be stagnant if it’s below 32 degrees Fahrenheit.
2. Cover the swimming pool. Covering the pool preserves the warmth while preventing the external freezing temperatures from causing long-term problems. The cover also insulates your above-ground swimming pool. Thankfully, all winter covers stretch around the edges and cover the outer material.
3. Consider running the heater during the coldest days of the month. Your pool heater can prevent freezing issues. There’s no doubt that a frozen pool takes a long time to recover. However, using a heater will thaw the ice and prevent cold water from freezing. You can choose a gas-powered heater or a solar-powered heater.
4. Switch to a saltwater swimming pool. Saltwater doesn’t freeze as quickly as freshwater. In fact, saltwater can dip about five degrees Fahrenheit colder than freshwater pools before freezing. Saltwater pools use NaCl to chlorinate the swimming pool. It makes the water much softer without reducing the sanitizer’s effectiveness.
5. Close unused valves during the winter. Some above-ground pools have multiple valves leading to rooftop solar, additional plumbing, etc. Make sure the pool, filter, and heater are the only things on your equipment bad that get water flow (and the salt cell if you have one).

A frozen above-ground pool will face all sorts of problems, including cracks, tears, etc. Following the aforementioned process will keep your pool in good condition throughout the coldest months. Remember that the water has to be below 32 degrees Fahrenheit for a few hours before frost appears. If your pool doesn’t get that cold, it might never freeze.

Is It Okay for an Above-Ground Pool to Freeze?

It’s not okay for an above-ground pool to freeze because it can damage the plumbing, equipment, and liner. Frozen water can also crack the support beams and inflatable rings around the swimming pool. Extreme temperatures can permanently damage above-ground pools from long-term exposure during the winter.

If your above-ground pool freezes, don’t turn on the pump until you thaw the plumbing. Pour hose water over the pipes and insulate them if necessary. Once the water thaws, turn on the pump to circulate the water until it’s much warmer. Turn on your heater if you have one. It’s important to prevent the water from freezing once it thaws.

The good news is that many swimming pool pumps have antifreeze settings. These settings automatically turn on the pump when it gets too cold.

Pro Tip: Never use antifreeze in a swimming pool. It’ll throw off the chemicals, damage the plumbing, and ruin the equipment. Some people swear by antifreeze in their pools, but it’s not worth the risk.

Jonah Ryan

Jonah has worked for several years in the swimming pool industry installing and repairing equipment, treating pools with chemicals, and fixing damaged liners. He also has plumbing and electrical experience with air conditioning, ceiling fans, boilers, and more. When he’s not writing for Temperature Master, he’s usually writing for his own websites, LawnCareLessons.com and DIYByHand.com.