If you’re preparing to winterize your pool or looking for ways to protect it during off-seasons, you’ve probably come across the term “air pillow”. But what exactly is it? Is it essential? And do I need an air pillow under my pool cover?
In this comprehensive guide, we’ll explore the role of air pillows under pool covers, discuss when they’re necessary, and help you make an informed decision tailored to your specific pool and climate needs.
Understanding the Purpose of Pool Covers and Air Pillows
Before diving into whether or not an air pillow is necessary, it’s important to understand the main purpose of a pool cover, and how an air pillow supplements that function.
What Is a Pool Cover?
A pool cover is a protective layer placed over a swimming pool, primarily to:
- Reduce evaporation
- Minimize debris accumulation
- Prevent accidents and unauthorized access
- Maintain water temperature and chemical balance
- Protect the pool during seasonal closures
There are various types of pool covers, including safety covers, winter covers, and solar covers. The need for an air pillow can vary depending on the type of cover and the seasonal conditions you face.
What Is an Air Pillow?
An air pillow, also known as a winter air pillow or expansion pillow, is an inflatable device placed under a pool cover before winterization. Its primary purpose is to absorb ice expansion during freezing temperatures.
When water freezes, it expands. If left unchecked, the pressure from ice forming below a tightly secured pool cover can cause serious damage to both the pool walls and the cover itself. By creating a cushion or air space, the air pillow allows for controlled expansion, reducing stress on the pool structure and cover.
Do I Need an Air Pillow Under My Pool Cover? The Short Answer
In most cases, especially in cold or freezing climates, it is highly advisable — and in many cases necessary — to use an air pillow under your winter pool cover.
However, the exact need can depend on several factors:
- The type of pool (above-ground vs. in-ground)
- The type of cover (safety vs. mesh winter cover)
- The climate in your region
- The pool closure method (drained, winterized with antifreeze, etc.)
Before making a final decision, let’s break down key considerations.
Why an Air Pillow is Often Necessary
Now let’s explore the main reasons pool owners should consider using an air pillow when closing their pools for the winter.
1. Prevents Cover Damage from Ice Expansion
As previously mentioned, water expands by about 9% in volume when it freezes. When this happens under a tight-fitting winter cover, the resulting hydrostatic pressure can:
- Tear or puncture the cover material
- Warp or bulge in-ground pool walls
- Cause structural damage in above-ground pools
An air pillow provides a buffer zone, reducing the risk by allowing the expanding ice to push into the pillow rather than stressing the cover and pool.
2. Helps Preserve Pool Shape and Integrity
In-ground pools are generally more robust than above-ground versions, but still vulnerable during harsh winters. Without an air pillow, pressure from ice buildup may deform the pool walls or damage the liner, especially in vinyl-lined pools.
Above-ground pools can suffer even more. Without a space for ice expansion, the walls might bow outward, leading to potential collapse or damage to the pool frame.
3. Reduces Water Volume and Debris Below Cover
When properly positioned, an air pillow slightly elevates the center of the cover, encouraging rainwater and melted snow to drain to the edges rather than pooling in the center.
This built-in slope keeps the cover from sagging excessively, which can prevent:
- Accumulation of standing water
- Debris buildup
- Mold or mildew growth
- Stretching and weakening of the cover material
4. Eases Spring Opening Process
Without an air pillow, the pool may have a large block of ice beneath the cover. Thawing, removal, and refilling can become time-consuming and labor-intensive.
With a pillow in place, the cover remains suspended, ice displacement is minimized, and the pool’s water level is easier to manage in spring. The reduced debris also means less cleaning time and lower chemical demand after cover removal.
When You Might Not Need an Air Pillow
While air pillows are very beneficial, certain situations allow pool owners to skip using one:
1. Pools Closed with a Lowered Water Level
One of the primary reasons for using an air pillow is to give ice somewhere to expand. However, many pool professionals recommend draining the water level 4–6 inches below the skimmer before winter cover installation. When properly done, this method avoids major ice pressure issues.
If you follow this method meticulously and live in a moderately cold climate, you may not need an air pillow.
2. Mesh Covers and Free-Draining Covers
Mesh winter covers allow water to pass through rather than accumulate. If the cover isn’t airtight and water can freely drain, hydrostatic pressure buildup is minimized.
While the cushioning benefit of an air pillow still helps, it’s less critical when a mesh cover is used and adequate draining is in place.
3. Warm Climate Zones with No Freezing
If you live in a region like Southern California, Florida, or Arizona, where temperatures rarely dip to freezing points, ice expansion is not a concern. In these cases, an air pillow might still help with covering control and water management, but is not essential.
How to Choose and Install an Air Pillow
If you’ve determined that an air pillow is needed, finding the right one and installing it properly is essential.
Size of the Air Pillow
The size of the air pillow depends on the pool size and shape. As a general rule:
| Pool Size | Recommended Air Pillow Quantity |
|---|---|
| Under 12 ft diameter | 1 pillow |
| 12–16 ft diameter | 2 pillows |
| 16–20 ft diameter | 3 pillows |
| 20–30 ft diameter | 4+ pillows |
For rectangular pools, place multiple pillows evenly spaced across the deepest area — not the shallow end — where ice buildup is most likely.
Material and Durability
Look for heavy-duty, UV- and puncture-resistant air pillows, often made from materials like PVC or heavy plastic. These ensure the pillow can withstand freezing temperatures and avoid burst risks.
Also, ensure the air pillow includes a valve for inflation, and attaches safely to prevent floating to the edge or sinking.
Installation Tips
Here’s a step-by-step guide for correct air pillow placement:
- Balance your water level. Before installing the air pillow, ensure your water level is appropriate — usually just a few inches below the skimmer.
- Inflate the air pillow. Do not over-inflate; leave some room for natural expansion and contraction.
- Place in the pool’s deepest section. Center the pillow where ice pressure will be highest. For rectangular pools, place slightly wider than center across the width, not lengthwise.
- Secure the air pillow. Use provided anchors or rope systems to ensure it doesn’t shift during strong winds or cover installation.
- Apply and secure the pool cover. Once the pillow and cover are in place, properly tension the cover, ensuring it’s taut but not overly stretched.
Air Pillow Alternatives for Winter Pool Covers
If you’re looking for alternatives to a traditional air pillow, a few options can help manage hydrostatic pressure under a pool cover.
1. Water Pillows (Water Bags)
Unlike air-filled ones, water pillows are heavy bladders filled with water and placed strategically in the pool. They compress under expanding ice, effectively reducing pressure on the cover.
They’re especially easy to handle in cold conditions, don’t risk popping, and maintain shape better in windy environments.
2. Snow Rakes and Regular Maintenance
In some climates where snow melts and refreezes often, manually clearing snow from covers can help. However, this requires a mesh cover, not a solid one, and does not eliminate the risk of ice expansion entirely.
3. Self-Draining Covers
Some premium covers are designed to channel water toward the edges through internal tension systems and permeability controls. While these help, they’re ineffective against ice buildup, so still pairing them with an air pillow is ideal.
Best Practices for Pool Winterization
To ensure a long life for your pool and cover, follow these additional winterization best practices:
Maintain a Balanced Water Chemistry
Before closing, test and balance your water for:
- pH: 7.4–7.6
- Alkalinity: 80–120 ppm
- Calcium hardness: 200–400 ppm
- Sanitizer (chlorine or bromine): 1–3 ppm
Proper chemistry prevents issues like corrosion, scaling, and algae buildup beneath the cover.
Use Winterizing Chemicals
Adding a winter algaecide, non-staining winterizing chemical kit, or a shock treatment before covering helps keep the water clean and stable under the cover.
Lower Water Level (if applicable)
As mentioned earlier, lowering water below the skimmer helps prevent freezing-related damage, especially when an air pillow isn’t used.
Use Cover Clips or Water Bags Around the Edges
Stabilizing the edges of the cover keeps it in place and prevents wind-lifting or ice heaving. Use cover clips, water bags, or anchors to ensure firm tension.
Regular Winter Maintenance (if accessible)
Even after covering, occasionally check for:
- Sagging or pooling water
- Debris accumulation
- Cover tension
- Ice buildup
A quick adjustment might mean the difference between a well-protected pool and costly early damage.
Conclusion: Do You Need an Air Pillow Under Your Pool Cover?
So the answer to the question “Do I need an air pillow under my pool cover?” is:
In most cold to freezing climates where ice expansion is a concern and a solid pool cover is used, yes — using an air pillow under your winter pool cover is highly recommended.
It serves as a pressure buffer, protects the pool structure, maintains cover integrity, and simplifies pool opening in spring.
However, for mild climates or when using a mesh cover with lowered water levels, an air pillow might not be strictly necessary — but it still provides added peace of mind.
Ultimately, investing in a quality air pillow during pool winterization is a small expense with a big payoff, potentially saving you hundreds or even thousands in cover damage, liner repairs, or structural replacements.
Final Tip:
Always follow your pool manufacturer’s instructions and consult with local pool professionals to meet the needs for your specific setup.
Takeaways
- Use an air pillow to absorb ice pressure in freezing weather.
- Air pillows reduce strain on pool covers and protect pool walls and liners.
- Air pillows are not required in warm climates or with proper water draining under mesh covers.
- Proper inflation, placement, and securing are vital for effectiveness.
Now that you know the answer to “Do I need an air pillow under my pool cover?”, you’re ready for a safer, smoother winter pool season.
What is an air pillow and why is it used under a pool cover?
An air pillow is an inflatable device placed under a winter pool cover to create a buffer between the cover and the surface of the pool water. Its primary purpose is to absorb the pressure caused by expanding ice during the colder months. Without this cushion, the cover may come into direct contact with the ice, which can lead to stress on the cover, causing it to tear or stretch. Additionally, it provides space for ice to expand without pushing against the sides of the pool, which can contribute to structural damage.
Inflated air pillows also help reduce the accumulation of standing water on top of the cover by creating a raised area that allows water to drain toward the edges. This helps prevent the added weight of water from damaging the cover or placing undue stress on the pool walls. Most pool experts recommend using at least one air pillow — more for larger pools — to ensure adequate protection throughout the winter season. The number and placement of air pillows should be based on the pool’s size and shape, with larger pools requiring multiple pillows for balanced coverage.
Can I skip using an air pillow if I have a safety cover?
Safety covers are designed to withstand more pressure and are often considered more durable than traditional winter covers, but they do not eliminate the need for an air pillow, especially in areas with freezing winters. Even though a safety cover is tightly secured and can support weight, the expansion of ice can still exert pressure on the pool walls and the cover itself. Using an air pillow creates a buffer zone that allows ice to expand upward rather than outward, minimizing potential damage.
If you use a safety cover and choose not to use an air pillow, it is vital to keep the water level significantly lower than usual to account for ice expansion. However, this may not always be the most practical solution and can affect the balance of chemicals in the pool water below the cover. For optimal protection and to ensure your pool is in good condition come spring, it is still highly recommended to use an air pillow under a safety cover in freezing climates.
What materials are air pillows made from?
Air pillows are typically constructed from heavy-duty vinyl or PVC, which are durable and resistant to punctures or leaks in the pool environment. These materials are chosen to withstand the pressure of expanding ice and the general stress of being submerged in pool water for several months. Many air pillows also feature reinforced seams and thick construction to handle the weight and movement of ice without tearing or deflating over time.
Some air pillows also have textured or ribbed surfaces designed to reduce water accumulation and encourage proper drainage away from the center of the cover. This feature further prevents the pooling of water on top of the winter cover and reduces the chances of debris buildup. While the materials and design may vary slightly between manufacturers, the overall goal remains the same: to provide a strong, buoyant cushion that protects both the cover and the pool during the winter months.
How do I install an air pillow under my pool cover?
To install an air pillow, start by inflating it according to the manufacturer’s instructions, making sure not to overinflate. Once it’s firm but not rigid, position it in the center of the pool or strategically around the pool depending on its size and shape. The air pillow should float freely on the water surface before the cover is installed. It’s essential to place it before the winter cover is fully secured so that it functions correctly when the water freezes.
After the air pillow is in place, carefully stretch the pool cover over the entire pool, ensuring it sits snugly but allows the air pillow room to expand if ice forms. Proper placement will help absorb pressure and prevent undue stress on the cover and pool structure. Some pool owners use multiple air pillows to provide additional protection for larger pools or irregularly shaped ones. Once installed, securing the cover with water bags or anchors will help maintain the position of the pillow and cover throughout the winter.
What happens if I don’t use an air pillow with my winter cover?
Without an air pillow under a winter cover, ice can expand and press directly against the cover and pool walls, potentially causing damage to both. As water freezes, it expands in all directions, and without space to move, it can push against the pool shell, potentially causing cracks or bulges. This pressure may also strain the winter cover, leading to rips or deformation that may compromise its ability to protect your pool.
Additionally, the lack of an air pillow often results in water collecting on top of the cover, which can add significant weight and lead to sagging or tearing if not removed regularly. Moreover, if the cover sinks too close to the water surface, debris can become trapped underneath, complicating the spring cleaning and opening process. While it may seem like an optional accessory, the air pillow plays a critical role in winterizing your pool and is highly recommended in freeze-prone climates.
Can I reuse my air pillow next winter?
Yes, most air pillows are designed for multiple seasons of use if handled and stored properly during the off-season. After winter ends, carefully deflate the air pillow and rinse it with clean water to remove any pool chemicals or contaminants. Once dry, store it in a cool, dry place away from direct sunlight or sharp objects that could degrade or puncture the material over time.
Before using the air pillow for the following season, inspect it for signs of wear, such as small leaks, cracks, or weakened seams. Proper maintenance and storage will help ensure that the air pillow remains functional and effective for future use. While some pool owners prefer replacing the air pillow every few years as part of routine maintenance, there’s no need to discard it prematurely if it’s still in good condition.
How many air pillows do I need for my pool?
The number of air pillows required depends primarily on the size and shape of your pool. For standard in-ground pools, most manufacturers recommend using one to three air pillows, with additional pillows added for pools larger than 20 feet in length. Oval or irregularly shaped pools often require more than one air pillow to ensure even coverage and pressure absorption to protect the cover and the pool structure adequately.
Using multiple air pillows distributes ice expansion more evenly and prevents sagging in specific areas of the cover. Some pool owners find that placing one in the center and additional ones toward the far ends or deep end of the pool offers the best protection. Always consult the air pillow manufacturer’s recommendations or your pool professional if unsure, as overwintering without the correct number of air pillows can lead to unnecessary maintenance and costly repairs.