Do Liquid Pool Covers Work? Pros and Cons Explained

Do not underestimate just how quickly water can decrease your core body temperature, even “warm” water on a hot sunny day. Some people who are more sensitive to the cold may find that they have to leave the pool early on account of the fact that they’re shivering.

There are various ways you can heat your pool so that it’s more tolerable to swim in for long periods of time – solar covers and solar rings are popular and affordable options. However, one unique product that you could also use is a liquid solar cover. Unlike a physical pool cover, liquid pool covers are invisible to the eye, keep your pool warm, and you can still swim in it.

This may sound too good to be true, but it has become quite popular in the pool community. So does it actually work, what are the pros and cons, and are they safe to swim in?

Indeed, liquid pool covers do work by covering the surface of your pool in a liquid that traps heat and reduces water evaporation. The ingredients used in a liquid pool cover are all found in nature, meaning it is all-natural and safe to swim in. A downside of this product compared to a regular pool cover is that it doesn’t keep debris out and its effectiveness can be impacted by the weather.

In this article, we’ll answer all of your questions about liquid pool covers in more detail to help you determine if it’s the right product for your pool.

How do liquid pool covers work?

Liquid pool covers work exactly how they sound – it is a liquid that you can pour into your pool that covers the surface, protecting the water below. Liquid covers reduce water evaporation which is the biggest source of heat loss, and the end result is that your pool will be warmer.

The more skeptical among you will ask the question: wouldn’t the liquid cover just mix with the pool instead of staying at the surface?

The answer is it doesn’t mix, and that’s because of the water-repelling fatty alcohol found in all liquid solar covers. Fatty alcohol is the magic behind liquid solar covers, and this is what rises to the surface to shield your water from evaporation. As part of the ingredients, a dispersant is used to help spread the fatty alcohol across the surface of your pool.

Adding a liquid pool cover is very straightforward. Simply follow the instructions on the label, and it should be something like this:

  • Make sure your pool pump is running.
  • Shake the liquid cover thoroughly.
  • Measure out the amount of product you need – typically you need 4 oz per 600-700 sq ft of pool space.
  • Pour the liquid cover into the skimmer for quick circulation.
  • Re-apply the liquid cover as needed, which is around once a week.

Liquid solar pool cover pros

Reduces evaporation

The main reason pool owners use pool covers, and a liquid pool cover is no exception, is to prevent evaporation. Liquid pool covers can reduce evaporation by as much as 50%.

Another interesting fact: around 70% of heat loss is due to evaporation. So by using a liquid pool cover, you’re killing two birds with one stone: conserving water while trapping precious heat that is lost to the air.

If you typically rely on gas or electric heaters to keep your pool warm, liquid pool covers can help you offset some of those costs over the course of a pool season.

Maximizes solar heat gain

In addition to the above, liquid pool covers do not hinder sunlight’s ability to strike the pool and transfer energy to it. Therefore, you can rely on free energy from the sun to provide heating instead of your pool heater.

Conversely, a physical solar pool cover can potentially block a significant portion of solar absorption depending on how transparent it is.

Converves water

With the surface covered, a majority of water evaporation can be prevented and this can result in huge savings in your water bill.

It is estimated that pools lose ¼” of water a day. Depending on how large your pool is, that can be as much as 100 gallons of water lost to evaporation a day.

Most liquid pool covers claim they can prevent 30-50% of pool water evaporation, and that still translates to dozens of gallons of water saved a day.

Safe to swim in

An obvious downside to physical covers is that you cannot swim in the pool while it is on. Furthermore, there is a drowning risk where if anyone were to fall into the pool while the cover is on, the cover can envelop the person and pose a severe drowning risk.

You might think that a liquid pool cover is no safer to swim in, but actually it is totally safe. The ingredients used in liquid covers are natural and pose no risk to your health.

Therefore, you can apply the liquid cover, immediately start swimming in the pool, and can reap the evaporation-reducing benefits immediately.

Easy to apply

The reason why one might prefer to use a liquid pool cover over a physical pool cover is how convenient it is to use.

For a physical pool cover, you are expected to cover up the pool when not in use, and then you need to take off the cover when you do want to use the pool. Even with a reel system, it can get annoying really quickly.

With a liquid pool cover, you just pour the amount you need into the pool skimmer once a week or so, and you’re done. It’s so simple and convenient.

Liquid solar pool cover cons


Liquid pool covers are much cheaper than a physical pool cover in the short-term, but are more expensive long-term.

That’s because liquid pool covers cannot be reused, whereas a physical cover can be reused for multiple pool seasons.

If you use the pool frequently and plan on doing so for many seasons to come, I highly recommend investing in a physical solar pool cover instead (make sure the bubbles are racing the right way).

The initial cost will be higher, but you can easily justify the cost the longer you use it for. Plus, it can keep debris out, which a liquid cover can’t.

No debris protection

One of the liquid cover’s greatest strengths is also a weakness – there’s nothing physically separating your pool water and debris, which means leaves, branches, dirt, insects, and other contaminants can still enter your pool.

Effectiveness dependent on weather

As mentioned, liquid pool covers rely on a thin film of fatty alcohol to remain atop the surface of the water to cover the water underneath and reduce evaporation.

However, on a windy day the fatty alcohol can be blown to one side of the pool, exposing a portion of the pool to the wind. During prolonged winds, you may have to add more liquid cover than usual.

Rain can also cause problems, since each droplet will temporarily open the cover up when it strikes the surface. Higher volumes of rainfall may require adding more liquid cover than usual.

Do liquid pool covers work?

In a study conducted by the California Polytechnic State University, where only two liquid cover products were tested against physical solar covers and solar rings, it was found that the liquid cover reduced water evaporation only by around 15% compared to no cover at all.

Comparatively, it was found that physical pool covers reduce evaporation by around 95%, and solar rings by 50%.

With that said, only two liquid cover products tested and the focus was only on water evaporation, so this is far from a comprehensive study.

It could be that the two liquid cover products tested were of lower quality and that higher quality liquid covers with significantly more evaporation protection exist. Or we can accept that, if water evaporation were your number one concern, then a physical pool cover is a safer bet.

Furthermore, this study does not account for any temperature increases that preventing evaporaton can lead to. In my experience, with a liquid cover on, my pool temperature is around 7°F warmer compared to no cover. However, a physical solar cover can warm water up by around 10-15°F, so it is still the superior option.

Ultimately, it is up to you to decide if the pros of a liquid cover outweigh the cons, or if you’d rather just spend the greater initial cost on a physical solar cover. Just make sure you also have a reel system in place to make putting it on and taking it off much more convenient.