Solar Pool Cover Bubbles: Up or Down?


Want to invest in a solar pool cover? Here is a guide to the right usage, choosing the correct size, thickness, and color.

Imagine being in a warm pool on a winter evening after a long work day, relaxing, isn’t it? However, the concern of heating a pool and the electricity bill could ruin the experience. But no worries, solar pool covers are there to our rescue; these use solar energy to warm up the pool and protect it from dust, debris, and harmful UV rays. Read the article to know more about selection and usage before getting your own.

Solar Pool Cover Bubbles: Up or Down?

To understand whether the solar pool cover bubbles are to be kept up or down we need to know the mechanism by which it works. The solar pool cover contains bubbles that trap air in them. This air trapped in the bubbles then warm up slowly, which is transferred to the water due to conduction which means transfer of heat from hotter to colder medium. Thus naturally warming up the water.

Why Your Solar Pool Cover Bubbles Should Always be Kept Downwards?

We have seen that the heat is transferred to the pool from the contact of the bubble on the cover with the pool’s surface. For optimal heat transfer, the air bubbles need to be kept facing downward. These bubbles serve as energy agents capturing the sun’s warmth and seamlessly transferring it to the water creating an oasis in your pool. When properly oriented these bubbles act as magnets, for heat maintaining the warmth of your pool water. Therefore, to make the most of your pool cover effectiveness it is important to ensure that the bubbles are positioned downward.

However, if the bubbles face upward several problems can arise. They may overheat, leading to a faster breakdown of the solar cover. Let us look at the problems:

1. The purpose of purchasing solar pool cover to heat up the pool would be defeated, as the bubbles would not be in contact with the pool and therefore not heating it.

2. The bubbles in the solar pool cover may bust and damage your cover because the air trapped in the bubbles will heat up and expand. It would not get a cooler medium to transfer the heat thus resulting in the bursting of the bubbles.

So, if you want to enjoy a warm pool you should always keep the solar pool cover bubbles down.

Cross-Reference: Bubbles breaking up and falling off underside

Best Pool Solar Cover Thickness

Solar pool covers come in different thickness variants mostly 8mil, 12mil, and 16mil. When it comes to finding the thickness of a pool cover, factors like durability, heat retention, and effectiveness come into play.

To understand it better, let us look at some of the major purposes that solar pool cover serves and which thickness variant will serve it best.

1. Heating of Pool

A solar pool cover with less thickness would allow more penetration of sunlight as compared to that of a cover with more thickness. If you live in an area with lower sun exposure, you should go for a thinner cover.

2. Weight of Solar Cover

A thicker solar cover would naturally weigh heavier than the thinner one. The purpose of purchasing a heavier cover may be because you live in a windy area where winds are less likely to blow off a thicker cover than a thinner one.

3. Protection from UV Rays

Ultra-violate rays from the sun damage the chemicals in the pool thus raising the expenses of redoing them frequently. A thicker solar pool cover would save the pool more from UV rays than a thinner one.

Considering these factors you may choose:

  • 8mil thickness for a warmer pool in less windy areas.
  • 12mil thickness medium range benefits of both the variants.
  • 16mil thickness for a more lasting pool cover, chemicals, and protection from strong winds.

Is Thickness the Only Parameter?

For covering the pool you need to look for the dimensions of your pool. For rectangular pools, generally 20 ×— 40 solar pool cover is the most demanded size which can be then trimmed as per your requirement. You can also go for an 18 ×— 36 solar pool cover variant for a smaller pool. For pools of irregular shapes, a larger cover can be cut in the shape to exactly cover the pool.

But the thickness of the cover alone is not sufficient, it also needs to be covered properly, with the right color to achieve the desired benefits.

Also Read: How to Roll Up a Solar Pool Cover

What Colour Solar Cover is Best?

pool cover

Apart from the thickness, the color of the pool cover determines the heat retention and protection of the pool. Black solar pool cover vs clear solar pool cover is the debate that draws upon your mind as soon as you think of buying one. But before answering that, we need to have in-depth knowledge about what colors are available and what purpose they serve the best.

1) Black Solar Pool Cover

The black solar pool cover offers opaqueness and high absorption capacity. This would also contribute to the retention of the heat in the pool. This feature makes it best for days with less and mild sunlight. The only drawback is that this cover may get damaged due to excessive heat retention.

2) Blue Solar Pool Cover

Blue solar pool cover is a translucent one that allows UV rays to easily pass through the cover providing some heat retention as well. As it offers both qualities to a certain extent, it is the most popular purchase and hence is available at a lower cost.

3) Clear Solar Pool Cover

A clear solar pool cover would cause more ultra-violate ray penetration and thus more warming up of the pool but it gives less retention. It lacks the efficiency of deeper penetration, so you would need good circulation. This would be better for a place with a long duration of day with good sunlight.

4) Blue-Silver Space Age Solar Cover

A space-age solar pool cover offers a hybrid solution to the disadvantage of heat retention by the blue solar pool cover. The blue side on the top provides heat penetration while the bottom silver side reflects and traps heat keeping the pool warm for a longer time.

5) Blue-Black Solar Cover

Combining the advantages of both the blue-black solar cover offers translucent and opaque features, thus heating the pool as well as retaining heat efficiently.

You can choose the color of the solar cover based on your primary purpose. If you want a heated pool and can compromise on longevity, opt for a black cover. Alternatively, choose a clearer cover if you have an abundance of sunlight and are looking for a long-term investment. You can also consider hybrid options if they align with your budget.

Also See: Solar Panel Patio Cover – Definition, Cost, Pros and Cons

Black Solar Pool Cover Vs Clear Solar Pool Cover 

Black solar pool cover and clear solar pool cover have their different purposes; utilizing the sun’s energy to heat the pool water. However, they achieve this goal in different ways and each type has its own set of advantages and disadvantages. Let’s compare them: 

1. Black Solar Pool Cover


  • Enhanced Heat Absorption: Black covers absorb sunlight converting it into heat energy. This can result in the heating of the pool water. 
  • Heat Retention: They effectively retain the heat, especially during cooler nights helping to maintain a consistent pool water temperature. 
  • Algae Growth Prevention: The dark color inhibits sunlight penetration, which can aid in preventing algae growth in the pool. 
  • Durability: Black covers are often made with materials making them more robust and long-lasting.


  • Reduced Light Penetration: The dark color restricts the amount of light that passes through potentially limiting plant growth and impacting the appeal of the pool area. 
  • Higher Water Temperature: While this may seem advantageous in some cases it can lead to warm water, for swimming purposes, particularly on scorching summer days. 

2. Clear Solar Pool Cover


  • Improved Sunlight Penetration: Clear covers allow more sunlight to pass through which helps aquatic plants thrive and maintains an appearance, for the pool area.
  • Reduced Heat Absorption: Clear covers absorb more heat making them beneficial in regions where excessive heat is not desired.
  • Aesthetically Pleasing: Clear covers do not alter the appearance of the pool allowing the beauty of the pool water and its surroundings to be fully visible.


  • Slower Heating: Compared to black covers, clear covers are less efficient at heating the pool water since they absorb and retain heat.
  • Potential Algae Growth: Due to increased sunlight penetration, clear covers may contribute to algae growth if proper chemical balance and maintenance are neglected.
  • Durability Concerns: Clear covers are often made of materials, and may be less durable when compared to black covers.

Also Read: Solar Panel for Pool Pump Installation, Operation and Benefits

Benefits of Getting a Solar Pool Cover

Solar Pool Cover Bubbles_Up or Down 1

Solar pool covers offer advantages to pool owners, such as: 

  • Heating the water: Solar pool covers harness the sun’s UV rays, which heat up the air trapped within their bubbles. This warmth is then transferred into your swimming pool water. It has been observed that solar covers can raise pool temperatures by around 10 to 15° F. 
  • Cost effective: By using solar pool covers, you can save money by eliminating the need for energy-consuming pool heaters. They also help in retaining pool water and reducing chemical usage. 
  • Minimizing water evaporation: With the aid of solar pool covers, you can significantly reduce water evaporation leading to savings on both your water bills and chemical expenses. 
  • Extending the swimming season: During winter months solar pool covers maintain warm water temperatures and thus extend your swimming season. 
  • Maintaining cleanliness: Solar pool covers act as a barrier against debris effectively reducing the time and money spent on cleaning efforts. 
  • Protecting your investment: By shielding your pool from elements, solar covers help minimize wear and tear on your equipment over time.
  • User friendly: Using solar pool covers is hassle-free; they are easily removable and replaceable, without any complications. 

In general, using a pool cover is a method to maintain your pool temperature, for swimming and lower heating expenses. Additionally, it offers advantages that can ultimately save you both time and money.

Investing in the right solar pool cover can save you a significant amount of money and energy. This article provides a clear understanding of whether to keep the solar pool cover bubbles up or down, the optimal pool cover thickness, and the best color for your specific requirements. Using this information, you can make an informed choice and enjoy your warm, clean pool with the help of a solar pool cover.

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