Are Liquid Pool Covers Actually Useful or Just Snake Oil? (Actual Data)

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Jumping into a cold pool can be refreshing on a hot day, but the frigid water is more likely to result in a short-lived experience.

While there are many options to keep your pool warm –such as bubble covers and solar rings— one of the more unique products is the liquid pool cover.  Unlike a traditional plastic cover, the liquid pool cover is invisible while still helping to keep your pool warm.  

While an “invisible” cover may sound a bit like snake oil, it has made a name for itself in pool culture.  But, is it actually worth the cost?

This article will explore how liquid pool covers work, along with liquid pool cover pros and cons.

We’ll also review data from several studies –including a personal one– to help you make ultimate determination as to whether the liquid pool cover is worth the price.

Without further ado, let’s hop into what exactly a liquid pool cover is.  

What is a Liquid Pool Cover?

A liquid pool cover is pretty much exactly what the name implies: a pool cover made of liquid.  

The liquid cover is used to help prevent evaporation of your pool water.  Evaporation is the largest cause of heat loss in the pool, so reducing evaporation will help keep the pool warmer.

The liquid cover is a single molecule thick and is invisible to the naked eye.  It sits atop the surface of the pool just like a traditional solar blanket in order to form a barrier that reduces evaporation.

Right off the bat, you may be wondering if this product is just a gimmick.  Wouldn’t the liquid cover just mix right into the water –how could it actually provide a barrier to evaporation?  

Looking at the ingredients provides insight as to how the liquid pool cover works. 

Liquid Pool Cover Ingredients

You’ve probably glanced at labels of various household products around the house and seen a multitude of unpronounceable ingredients.  While the principle of the liquid pool cover may lead you to believe that it too must also contain a lot of complex ingredients, this isn’t necessarily the case.

Commercial liquid pool covers contain ingredients that are biodegradable and safe for human and animal contact.  In other words, the products are safe to swim in!

Most liquid pool covers have two primary ingredients: a fatty alcohol and a dispersant.

Fatty Alcohol

Fatty alcohols are also known as long-chain alcohols.  Cetyl alcohol and stearyl alcohol are two types commonly found in the commercial liquid solar cover products.

The fatty alcohol is hydrophobic in nature.  This means the liquid cover will repel away from the water forcing it on top the surface of the pool.

The fatty alcohol is the primary player in the liquid solar cover.


The dispersant is also known as a carrier.  Isopropanol and calcium hydroxide are two types of dispersants often used in the commercial liquid solar covers.  

The purpose of the dispersant is to help spread the fatty alcohol across the top of the pool.  In order to prevent evaporation it is important that the cover encompasses as much of the surface as possible.

How to Use a Liquid Pool Cover

Now that we know what a liquid pool cover is, we’ll look at the simple process of how to use it:  

1 – Ensure pool pump is running

Having the pool pump running will help ensure that the cover can be circulated for quick coverage across the pool’s surface.

2 – Shake the liquid cover well

Before use, it is important to shake the bottle of the liquid solar cover well.  This will ensure the fatty alcohol and the dispersant are mixed together for optimal performance.

3 – Measure the quantity of liquid cover

The amount of liquid cover required will depend on the size of your pool.  It is important to follow the manufacturer’s instructions for appropriate dosage.  4 oz per 600 – 700 sq ft is common across several brands of liquid solar covers.

4 – Dispense the liquid cover

Follow the manufacturer’s instructions as to how the liquid cover should be placed into the pool.  A common location is to pour the liquid cover into the skimmer, which will ensure quick circulation back into the pool.

5 – Repeat application routinely

The liquid cover will break down over time, in which reapplication will be necessary.  A weekly application is generally required.  It’s best to set a reminder to ensure it gets re-applied on time to assure maximum effectiveness.

Liquid Pool Cover Pros and Cons

As with nearly all pool heating products, the liquid pool cover has pros and cons that you’ll want to consider:

Pro #1: Heat Conservation

The primary goal of the liquid pool cover is to prevent evaporation.  It’s estimated that 70% of heat loss in a pool is due to evaporation.

Using a liquid pool cover may reduce evaporation anywhere from 15 to 40%.  Reduction in evaporation will help your pool retain its precious heat.

Particularly for pools that use gas or electric heaters, this heat conservation can become a huge money saver over the course of a pool season.

Pro #2: Maximizes Solar Heat Gain

Pools absorb 75 – 85% of the sun’s energy striking the surface, which translates into heating.  A liquid pool cover will not hinder the absorption of the sun’s energy since the cover is completely invisible.

Conversely, bubble covers will reduce the amount of solar absorption anywhere between 5 – 40% depending on the transparency.

Pro #3: Water Conservation

Pools can easily lose up to ¼” of water per day due to evaporation.  This can equate to 100+ gallons per day for an average size in-ground pool.

Since liquid pool covers help reduce evaporation, this means less water will be disappearing from your pool.  

Environmental factors will impact how effective the liquid cover is able to reduce evaporation. Some liquid pool covers advertise up to 85% evaporation reduction, but this will greatly vary based on other factors (pool usage, weather, etc).  

Pro #4: Ease of Application

If you’ve ever used a standard solar blanket, you know how much of a hassle it can be to take it off the pool (and to put it back on the pool).  

This is where the liquid pool cover really shines.  There’s no fussing with a physical cover –it’s just a matter of pouring the liquid cover into the pool once a week or so.  It can’t get any easier than that!

Pro #5: Swim While It’s On

A solar blanket sitting atop the pool may be enough to persuade you from taking that quick dip in the evening, as you may decide it’s not worth the effort of removing it.  As soon as you do pull the cover off, you no longer have the protection it provides against heat loss.

A prime benefit of the liquid solar cover is that you swim with it in place.  There’s no taking the cover off, as it’ll move out of the way as you enter the water.  

While you’re swimming in the water, the liquid cover will move around you.  It will continue to remain at least partially effective while you’re swimming, and will reform atop the surface as the water returns to a calm state.

Pro #6: Safety

When dealing with traditional solar blankets, entrapment can be a concern.  If a person or pet tries to walk atop the cover, they could become entangled leading to potential drowning.

With the liquid pool cover, there is no risk of entrapment.  The product does not pose any increased risk of drowning 

Additionally, the ingredients that make up the liquid pool cover have been proven to be safe for swimmers without posing any increased health risk from exposure.

Pro #7: Water Health Indication

When leaving a traditional pool cover in place for more than a few consecutive days, it’s not uncommon to find algae growth or cloudiness when the cover finally comes off.  Some of this could be caused by lack of visibility of water health, along with inability for the pool water to naturally degas.  

A liquid pool cover will allow you to keep an eye on the water such that you can immediately take action on any signs of abnormalities.  It also allows for natural circulation and breathability of the pool.  

Pro #8: Price

The cost of a liquid pool cover is generally cheaper to purchase for the course of a pool season versus a new solar blanket.

For an 18 x 36 rectangular pool, 2-3 quarts of liquid pool cover may be all that’s needed to get you through a five month swim season.  

However, if you’re able to stretch the lifespan of a blanket for two or more seasons, the cost of a liquid pool cover over the same amount of time may exceed the cost of the blanket.  Don’t forget to add in the cost of a solar cover reel if you’re trying to compare costs between the liquid pool cover and the solar blanket. 

Con #1: Affected by Weather

A liquid pool cover relies on its mono-molecular film to remain atop the entire surface for maximum effectiveness.  

A windy day can cause the liquid cover to accumulate on one side of the pool, allowing for a portion of the pool to be exposed to more evaporation.  In the event of extended periods of wind, it may be necessary to add more liquid pool cover at a higher frequency than normal.

Rain can also disturb the liquid cover as each droplet will temporarily open the cover up.  High volumes of rain may also require addition of liquid pool cover sooner than scheduled.

Con #2: Re-Application

While application of the liquid pool cover is an extremely simple task, remembering to actually add in the cover on a routine basis may be another story.  

If you’re unable to keep a rigid schedule of adding in the liquid cover, the effectiveness of it will greatly diminish in your pool.

Since the cover won’t provide any visual cues as to when it’s starting to dissipate, it’s recommended that you set a schedule or reminder to help ensure the liquid cover is routinely added on time.  

Con #3: No Protection from Debris

While the primary purpose of a solar blanket is to prevent evaporation and keep the pool warmer, they also provide the benefit of keeping debris from falling into the pool.  

The liquid pool cover will not provide any protection against dirt, leaves, bugs, or other unwanted items from falling into the pool.

Does the Liquid Pool Cover Actually Work?

With some pretty impressive manufacturer claims as to the effectiveness of liquid pool covers, you may wonder why anyone would ever consider anything but a liquid pool cover.  

This raises the question as to whether the liquid pool covers actually work?

Scientific studies have proven that liquid pool covers do provide measurable benefit during routine use –however, it’s best to temper your expectations.

Cal Poly Scientific Study

An extensive study of various types of pool covers was conducted by the California Polytechnic State University in 2015.  The study included two types of liquid pool covers along with traditional solar blankets.  

Both of the tested liquid covers achieved approximately 15% evaporation reduction compared to a pool with no cover at all.  This is significantly less than the 95% evaporation reduction achieved by standard solar covers.

The study did not directly capture data around change in temperature of pool water (heat loss).  However, its data around evaporation indicates that the heat loss reduction would likely have been in the 10-15% range as well.

Information & Energy Inc. Study

In 2005, a 40-week study was conducted by IES for the Heatsavr™ liquid pool cover product.  The study was performed with a commercial pool to determine whether the liquid cover could provide energy savings with the pool’s natural gas heater.

The study concluded that the liquid cover would provide energy savings of 13% compared to an uncovered pool.  This energy savings data aligns fairly close to the evaporation data in the Cal Poly study.

The IES study also indicated that the liquid solar cover was not as effective as a traditional solar blanket.  However, no specific data was provided as to the difference in effectiveness between the two styles of pool coverings.

At-Home (Personal) Study of Liquid Pool Cover vs Solar Blanket

Over the past 15 years of owning a pool, we had been users of the traditional bubble solar blankets.  We pretty much were in a routine of replacing the solar blankets every couple of years due to the inevitable cover deterioration.

We also have a solar heater, in which it’s important to retain the heat on cool nights to allow for continued buildup of temperature over the course of several days.

With solar blankets doubling in price over recent years, we decided it was time to give the liquid pool cover a shot rather than purchase a new blanket.   

We purchased the Natural Chemistry Cover Free, which comes in 32-ounce containers.  The product is labeled with the following benefits:

  • Reduces evaporation by up to 85%
  • Prevents heat loss by up to 70%

These are some pretty bold claims that rival a traditional solar blanket!  We were excited to see if this could be a long-term replacement to the more cumbersome solar blanket.  

The product instructions specify an addition of 4 oz for every 675 square feet of pool surface area on a weekly basis.  

Our 18 x 36 oval pool has a surface area of 600 square feet.  We decided to stick with 4 oz addition on a weekly basis to keep the dosing simple.  This means we should get about 8 weeks of liquid pool cover per quart.

Although we knew we’d get a rough feel of how well the liquid cover works for our pool through normal usage across a season, we decided to perform a quick study of our own in trying to better measure it.

Test Setup

Liquid Pool Cover Bucket Test
Liquid Pool Cover Test (Left to Right: Tub #2 – Liquid Cover, Tub #1 – No Cover, Tub #3 – Blanket)

For our study, we utilized three identical 18-gallon storage tubs filled with 16 gallons of water:

  • Tub #1: Water without any pool cover (our control sample)
  • Tub #2: Water with liquid pool cover
  • Tub #3: Water with solar blanket 

The tubs were placed in a location that receives sun for approximately 10 hours a day.

The starting water level for each tub was marked inside the tub in order to measure changes in water level.

Test Method

Testing was performed in early June here in Michigan.  It was conducted over the course of 7 days.

The change in water level was measured in each bucket after 7 days to determine the amount of evaporation that occurred.  

Temperature was recorded daily for informational purposes.  However, it’s important to note that the tubs are not insulated and allow for quicker fluctuation of temperature than a standard pool. This means that the actual temperature value of Tubs #2 and #3 is not a true portrayal of pool cover effectiveness, but can be used for relative comparison against our control sample. 

Test Results

The change in water level along with average temperature for each tub is summarized here for the 7-day test:

ContainerChange in Water Level (in.)Average Temperature (°F)
Tub #1 (No Cover)-11/1678.2
Tub #2 (Liquid Cover)-9/1679.3
Tub #3 (Solar Blanket)-1/1685.4

From the data, it’s calculated that the liquid cover provided an 18% reduction in evaporation compared to no cover at all. The solar blanket provided a 90% reduction in evaporation compared to no cover.

It is also seen that the average temperature of the water was 1.1°F warmer when using a liquid cover compared to no cover. The solar blanket water was 7.2°F warmer than no cover.

Test Conclusion

The data collected in our personal study mirrors results similar to those of the more controlled scientific studies summarized earlier in this article.

Our study found that the liquid pool cover does provide some measurable reduction in evaporation compared to no cover at all.  

However, the traditional pool cover significantly outperformed the liquid pool cover in reducing evaporation and maintaining temperature.

Should You Buy the Liquid Cover for Your Pool?

Visible Evaporation from Pool with Liquid Pool Cover (Water Temp 71°F, Air Temp 54°F)

Hopefully the rundown of pros and cons along with the data from the studies has helped provide you with perspective on the liquid pool cover. 

It’s thoroughly proven that the liquid cover will not compete with a traditional bubble cover when it comes to preventing evaporation and heat loss in your pool.  So, if you’re open to using a standard pool cover then it should be a simple choice.

However, if you’re totally against dealing with a standard cover, then a liquid cover can still provide you with benefit. 

For instance, the U.S. Department of Energy estimates an average cost of $3,200 to keep a pool in New York at 82°F all season long using a gas heater without a pool cover.  By using a liquid cover, the cost could be reduced by upwards of $400 if achieving the 13% energy reduction from the IES study!  This makes the liquid pool cover an easy investment.

Better yet, it may also be worth considering using both a standard cover in combination with the liquid cover.  The liquid cover could provide you with some benefit when the pool is in use and the standard cover is removed.  

Final Takeaway

Liquid pool covers can provide modest benefit in helping to keep the pool warmer by reducing evaporation.  They can also provide some key benefits that a traditional pool cover cannot offer –such as cheaper initial cost, ease of use, and safety from entrapment.

However, do not expect a liquid pool cover to outperform a traditional pool cover when it comes to heat retention and evaporation reduction.  The traditional pool cover has been proven to be several times more effective than a liquid pool cover through funded studies (along with my quick study).

If you have no desire to deal with a traditional pool cover, a liquid pool cover is a decent option to consider as it is better than no cover at all.  Otherwise, just know that a liquid pool cover is only one of many ways to keep your pool warm without a heater.

Happy Swimming (in Warm Water)!

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