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Water Care Advice

How to Winterize Your Pool

How to Winterize Your Pool

Knowing how to winterize a pool is crucial because it can save you time and money. Your pool provides you and your family with endless fun and memorable moments, so it's crucial to protect this part of your property during the cold winter months. Winterizing your pool protects its structure, pipes and elements from freezing water, and it ensures your water's chemistry remains balanced until spring. Continue reading to learn more about how to close down your pool.

Why Should You Winterize a Pool?

Preparing your swimming pool for winter is essential because it saves you time and money on potential repairs, and it makes it easier to open your pool when warm weather returns. Winterizing your above-ground or in-ground pool prevents damage and protects the following pool elements:

Structure and Walls

Structure and Walls

Above-ground pools can crumple in freezing temperatures. If water freezes inside the pool and forms an ice sheet, it can place outward pressure on the pool's walls. This issue can also occur in the pool's skimmer. The ice sheet can damage the pool's walls and collapse its structure if the ice sheet tilts, heaves or slips in the pool. Winterizing chemicals can prevent water from freezing, protecting your pool from this potential structural damage. 


Closing your pool for the winter protects its pipes from frozen water. Water expands in freezing temperatures, which can damage pipes. Winterizing a pool lowers its water level below the skimmer line, ensuring water exits the pool's pipes. Above-ground pipes and pumps can freeze within an hour after temperatures drop below freezing, but winterizing your pool before temperatures fall can prevent this damage. 


Pool filters are also subject to pressure damage in freezing temperatures. Pool filter tanks can typically handle some amount of pressure, but not expanding ice. If water freezes inside a filter tank, the following damage can occur:

  • The filter tank can crack.
  • The DE filter or cartridge's clamp ring could break.
  • The multiport valve flange could leak or detach from the tank.

Winterizing a pool filter prevents damage to the filter tank, clamp ring and multiport valve flange. 


Protecting your pool's pump is crucial because it saves you money on costly repairs. Replacing a pump can be expensive, so you should always ensure you prepare your pump for winter. 


Pool heaters are also vulnerable to winter temperatures. Polymer and cast-iron heaters can quickly snap when temperatures drop below freezing. To prevent damage, you can turn off the power and drain the heater before winter begins.


Underground pipes can freeze and crack, leaving space for leaks that can damage your property. Gaining access to underground pipes may require a messy excavation project. Winterizing your pool prevents pipe damage, so you can enjoy more peace of mind when spring returns.

Do I Need to Winterize My Pool?

Some pool owners in warmer climates can leave their pools open year-round, but people in colder climates must close their pools for the chilly winter season. Closing your pool is essential if you live in an area where temperatures fall below freezing for extended periods. 

When to Winterize Your Pool

When to Winterize Your Pool

Timing is an essential element of pool winterization. If you wait too long, the cold temperatures could damage your pool or its equipment. However, if you close it too early, warmer temperatures could support algae growth. You should winterize your pool when temperatures are above freezing but cold enough to prevent algae growth. 

The right time to close your pool depends on your home's location, but it's typically best to start the winterization process when temperatures fall below 65 degrees Fahrenheit and consistently remain below this temperature. 

What Do You Need to Winterize a Pool?

To properly winterize your pool, you will need the following supplies:

  • Pool vacuum
  • Water testing kit or a pool chemical monitoring device
  • Pool shock chemicals
  • Algaecide
  • Wing nut
  • Rubber plug for the return line
  • Skimmer cover
  • Inflated air pillow
  • Pool cover
  • Tools for removing ladders and handlebars

How to Test Your Pool's Water

Before winterizing your pool, it's essential to test and balance the water. You can test your water using test strips, a liquid pool test kit or an automated monitoring device

While pool owners commonly use test strips or liquid kits to test their water, an automated monitoring device facilitates more convenient and effective testing. A wireless pool chemical monitoring device offers faster and more accurate results than other test methods. Test strips take time to read and require pool owners to identify specific colors, which can lead to human error if people perceive colors differently. Wireless monitoring devices eliminate the need to read test strips. 

A monitoring device is also more accurate because it measures the water throughout your pool rather than merely the water surface. Modern testing devices sit in pool skimmers, providing a more comprehensive reading of the chemicals in pool water. 

Monitoring devices also provide longevity and reliability. Testing strips can become unstable when they expire or become exposed to water or sunlight, but pool owners can use monitoring devices to receive accurate results without worrying about exposure or expiration.

To test your pool water with an automated monitoring device, connect it to your home's Wi-Fi and download the corresponding app to receive directions and precise readings. Follow the directions to install the device in your pool's skimmer, and rest assured that you will gather accurate readings of the water. Before winterizing your pool, the water should be at the following levels.

  • pH: Make sure your pool has a 7.4 to 7.6 pH level. 
  • Alkalinity: The pool should have 80 to 120 parts per million alkalinity, but 125 ppm is ideal.
  • Calcium hardness: The pool's calcium hardness should fall between 150 and 400 ppm.
  • Chlorine: Make sure the chlorine level is between one and three ppm.

Check your monitoring device's readings to ensure your pool is at the proper levels. If so, you can begin the winterization process. If the levels are off-balance, you can implement these tips.

  • High acid level: If the water's pH level is too high, you can balance it with a base. Muriatic acid or sodium bisulfate can neutralize your pool's pH level.
  • Low or basic pH: Add a pH increaser if the water's pH level is too basic. You can use sodium carbonate or sodium bicarbonate to increase the pH depending on how low it is. 
  • Low alkalinity: If the alkalinity level is too low, you can balance it with sodium bicarbonate or an alkalinity increaser. 
  • High alkalinity: If the alkalinity is too high, you can decrease it to a balanced level with muriatic acid. 
  • Hard water: You can soften excessively hard water with softener chemicals. 
  • Soft water: If the water is too soft, you can harden it with calcium chloride or a calcium hardness increaser.

How to Winterize Your Pool

How to Winterize Your Pool

Winterizing your pool protects it during cold months, and proper winterization makes reopening your pool in the spring much easier. After testing your water's chemical levels, you can winterize your pool with the following steps.

Clean the Pool

Cleaning the pool and its filter is a vital step in the winterization process. Use a pool skimmer to remove any debris and clean the water. Next, brush the surface and use a pool vacuum to clear the floor of debris. Then, empty the skimmer baskets. Finally, you should backwash the filter and use a filter cleaner to chemically clean the filter's elements and media. 

Shock the Water

After cleaning the pool and filter, you can shock the water. Shocking is a process that adds a high dose of chemicals to the pool. These chemicals quickly eliminate waste matter such as algae and bacteria. Check your manufacturer's guidelines to shock your pool with the correct dosage. This step will raise the pool's chlorine level and destroy contaminants. 

It's crucial to use a high-quality pool shock during this step to prevent increasing the water's PH or calcium hardness. Using quality pool shock chemicals protects the pool from surface scale buildup during the winter. After shocking the pool, circulate the water for four or more hours to disperse the chemicals throughout the water. 

Pool shocking is also essential after heavy rain, and some pool owners in warmer climates need to shock their pools mid-winter. 

Prevent Algae Growth and Operate the Pump

Algae naturally grows in soil and plants, and the wind blows spores into pools. Keeping algae spores from blooming and growing into colonies protects your pool from this harmful material. To prevent algae growth, add the proper dose of algaecide according to your manufacturer's directions. This chemical prevents algae growth during the winter. Choose a high-quality algaecide that will not stain your pool's surface. 

After adding algaecide to your pool, run the pump for 24 hours so the chemicals can fully circulate. 

Winterize the Pool's Equipment

Storing your pool's equipment protects it from the elements and prevents weather damage during the winter. Follow your pool's manufacturer's directions to turn off its equipment, and partially drain the water until its level falls below the return lines and skimmer. Next, you must fully drain the equipment by removing the drain plugs.

After turning the equipment off, partially draining the pool and draining the equipment, you can remove the pool's chlorinator, hoses and pump for safe indoor storage. Storing these items indoors during the winter protects them from cold temperatures and snow.

If your pool has a sand filter, make sure you set its multiplier valve to a winter setting if possible. If the valve lacks a winter setting, you can place it between two settings and drain the filter by removing the plug. Your pool might also have a cartridge filter, in which case you should drain the filter, rinse it with a hose and take it indoors for safe storage. You should also drain your diatomaceous earth filters, clean the DE grids and reassemble the filter. 

Drain the Return Lines

Draining your pool's return lines clears them of water to prevent freezing pipes when outdoor temperatures fall below freezing. To drain the return lines, you must release the water and then blow air through them to expel any remaining water. 

You can expel water using a heavy-duty shop vac, a commercial air blower or an air compressor. You can also run antifreeze through the lines as an added protection layer. If you have an above-ground pool, you can remove your return lines and store them indoors to keep them out of the winter elements. 

Cover the Pool

A durable cover that properly fits your pool will protect it from the elements. Make sure your pool cover matches your pool's exact measurements for an accurate fit. 

To cover your pool, first remove the return line's eyeball fitting and seal it with a wing nut and rubber plug. Next, you should check to ensure the water level is below the skimmer and place a cover over the skimmer. Place an inflated air pillow in the center of your pool, and then use the pool cover to fully cover the top of the pool. Secure the cover with clips, then remove the pool's deck equipment such as ladders and handlebars.

An inflated air pillow is vital for above-ground pools, because frozen water can expand and collapse the pool's structure. You can winterize an in-ground pool without an air pillow, but adding one will give you an extra level of protection. 

Safely Store Chemicals

Check your pool chemical product labels to ensure you store them safely. You may need to dispose of some chemicals if their potency expires before you open your pool again in the spring. Store your other unused chemicals according to their product labels, so they remain in good condition for the spring. 

Continue to Monitor Your Pool's Chemistry

Testing your pool's chemistry at least weekly ensures your pool remains protected throughout the entire winter. You can use an automated monitoring device to keep track of your pool's pH, alkalinity, hardness and chlorine levels quickly and conveniently.

Maintain Your Pool With WaterGuru SENSE

Maintain Your Pool With WaterGuru SENSE

Winterizing your pool requires accurate chemical testing to prepare for cold temperatures. An automated pool monitoring device can deliver quick, precise pool readings to your cellphone, simplifying the winterization process. 

WaterGuru SENSE is a wireless pool chemical monitoring device that allows you to keep track of your water's pH, alkaline, calcium and chlorine levels without test strips. If you connect the WaterGuru SENSE system and your smartphone to Wi-Fi, you can receive precise results on your pool's chemical levels from any location and at any time. 

Test your pool easily from the comfort of your home throughout the winter to make sure it remains protected. Learn more about WaterGuru SENSE to simplify your pool winterization process.  

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