Closing Down a Pool: How to Winterize a Pool to Protect It Until Spring

As the temperatures drop and winter approaches, it's crucial to prepare your pool to withstand the cold weather. Proper winterization not only protects your investment but also ensures that your pool is ready to go when warmer days return.

Follow these steps on how to winterize your pool to help protect it throughout the winter and have it ready for the next swimming season.

1. Remove accessories and clean the pool thoroughly
2. Balance the water chemistry and add winterizing chemicals
3. Lower the pool’s water level
4. Remove and store the skimmer basket and attachments
5. Install a pool cover and pool cover pump
6. Monitor your pool throughout the winter

How to Winterize a Pool

While there are some differences between winterizing an in-ground pool and an above-ground pool, most of the process is the same. In general, you should close your pool once water temperatures consistently fall below 60-65°F.

Closing too early can reduce the effectiveness of winter chemicals and increase the risk of algae growth, while waiting too long can leave your equipment vulnerable to freeze damage. For the best results, plan to winterize your pool before the first hard freeze in your area.

1. Remove Accessories and Clean the Pool Thoroughly

Before winterizing your pool, remove ladders, chlorinator or saltwater generators for automatic pool cleaning and other accessories from the water. Rinse each item thoroughly to remove chlorine, salt and debris. For stubborn dirt or scale, use mild soap or baking soda, then rinse with clean water and allow everything to dry completely before storage. Store pool accessories indoors in a cool, dry location and keep them out of reach of children until the next swimming season.

Once the accessories are removed, clean the pool thoroughly. Brush the walls and surfaces to remove algae, biofilm and other buildup. Be sure to use the right brush for your pool’s surface:

• Vinyl liner or fiberglass pools: Use a nylon-bristle brush. Avoid steel brushes, which can damage the surface.
• Concrete, plaster or gunite pools: Use a stainless-steel or combination brush designed for tougher surfaces.

Next, vacuum the pool floor and use a skimmer to remove leaves, dirt and debris from the water’s surface. Empty and clean skimmer and pump baskets as well. Starting winter with a clean pool helps reduce the risk of algae growth, staining and other maintenance issues while the pool is closed.

2. Balance the Water Chemistry and Add Winterizing Chemicals

Properly balanced water chemistry helps protect your pool and equipment from staining, scaling and corrosion during the winter months. Before closing your pool, test the water and adjust these key levels:

• pH:2-7.8
• Total alkalinity: 80-120 ppm
• Calcium hardness: 200-400 ppm

Once the water is balanced, add a stain and scale inhibitor according to the manufacturer's instructions. These products help reduce mineral buildup and surface staining while your pool is closed. Run the pool pump long enough to circulate the treatment throughout the system—the inhibitor you choose will have specific details on the proper length of time.

Next, shock the pool to eliminate contaminants and prepare the water for long-term storage, whichc are available in chlorine and non-chlorine/oxygen-based formulations. There are three basic types of shock treatments available for your pool: calcium hypochloride, dichloroisocyanuric acid and potassium peroxymonosufate. Follow the directions on your chosen shock treatment and allow it to circulate completely before moving to the next step.

After chlorine levels have dropped below 5 ppm, add a winterizing algaecide to help prevent algae growth during the off-season. Run the pump as directed on the product label to ensure the algaecide is evenly distributed throughout the pool—this could be anywhere from 8-24 hours.

3. Lower the Pool’s Water Level

Use a utility pump like the Little Giant 5-MSP to reduce the water level in the pool. If using a solid pool cover, the water should fall 4-6 inches below the skimmer and return lines. If using a mesh pool cover, water should be 12-18 inches below the. This prevents water from freezing and expanding in these areas, which could cause damage.

Above ground pools: Never drain an above-ground pool completely, or the vinyl liner can become damaged.

4. Remove and Store the Skimmer Basket and Attachments

To help prevent freeze damage, remove the skimmer basket and store it in a clean, dry location for the winter. If your area experiences heavy rain, periodically check the skimmer to ensure excess water can drain properly.

Above-ground pools: Disconnect the hoses connected to the pump and filter, then allow all water to drain from the lines. Once the hoses are completely dry, store them indoors in a dry location. Seal open pipes with plugs or caps to help keep out moisture and debris.

In-ground pools: Turn off the pump and drain water from the pump, filter, heater and any other pool equipment according to the manufacturer's instructions. Use a shop vacuum or air compressor to remove any remaining water from the skimmer, return and plumbing lines. After the lines are clear and dry, install winterizing plugs to help protect the system from freezing temperatures.

For additional protection in colder climates, you may add non-toxic pool antifreeze to the plumbing lines after they have been cleared of water. Pool antifreeze should never be used as a substitute for properly draining or blowing out the lines, and it should not be poured directly into pool equipment.

Finally, consider installing a skimmer guard to help protect the skimmer from freeze-related damage and reduce stress on the plumbing system throughout the winter.

5. Install a Pool Cover and Pool Cover Pump

A properly installed winter cover helps keep leaves, debris and sunlight out of the pool while protecting the water throughout the off-season. Choose a winter or safety cover designed to withstand the rain, snow and ice common in your area, and make sure it is securely fastened to prevent shifting during winter storms.

A cover pump like Little Giant’s ACPC-1700 can help remove excess rainwater and snowmelt before it becomes a problem. Before closing the pool, inspect and test your cover pump to ensure it is operating properly, including any maintenance required for the float. Clean the pump, check the float mechanism and complete any recommended maintenance before installation so it is ready to perform throughout the winter.

Above-ground pools: Place an air pillow in the center of the pool before installing the cover. The air pillow helps relieve pressure from expanding ice and can make it easier to manage snow and water accumulation on the cover during the winter months.

A little preparation now can help protect your pool cover, simplify spring opening and reduce maintenance throughout the off-season.

6. Monitor Your Pool Throughout the Winter

Winterizing your pool doesn't mean you can forget about it until spring. Periodically inspect the pool throughout the off-season to make sure the cover remains secure and free of excessive leaves, branches and other debris. After heavy rain, snow or wind events, check for any damage and address issues promptly to help prevent larger problems.

Keep an eye on the water level and ensure the skimmer and drainage areas remain clear so excess water can drain when needed. If you're using a pool cover pump, periodically verify that it is operating properly and removing accumulated rainwater or snowmelt from the cover.

About once a month, inspect your pool cover, cover pump and other winterization equipment to confirm everything is functioning as intended. In regions where the pool water does not completely freeze, testing the water chemistry periodically can help maintain water quality and make spring startup easier.

A few quick checks throughout the winter can help protect your pool, reduce maintenance and make opening day go much more smoothly when warmer weather returns.

How Proper Pool Winterization Helps Protect Your Investment

Winterizing your pool is an important step in protecting your investment during the colder months. By thoroughly cleaning the pool, balancing the water chemistry, lowering the water level, adding winterizing treatments, removing and storing equipment, and installing a secure cover, you can help keep your pool in top condition throughout the off-season.

Regular inspections during the winter can help you catch potential issues early and ensure your cover, pump and other equipment continue to perform as intended. Taking these preventative measures now can make spring opening much easier, helping you save time, reduce maintenance and get back to enjoying your pool when warmer weather returns.