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How Are Pools Heated? Here Are the Best (and Worst) Methods

Heating your swimming pool can extend the swimming season and allow you to use the pool at night.

Nobody wants to dive into a freezing pool, but there are many ways to keep the water at a comfortable temperature.

However, it can be difficult to know which methods are efficient and which are a waste of time.

Pools are heated with solar blankets, heaters, liquid evaporation suppressants, and solar rings. Some pools use solar balls to slowly dispense a liquid solar blanket that preserves the heat in the water. Steer clear of questionable heating suggestions, such as using black tarps or garbage bags.

In this post, I’ll explain the best ways to heat your swimming pool and which methods aren’t worth the effort.

I’ll also cover a few alternative suggestions to keep your pool warm at night and during the winter.

What Is The Most Efficient Way to Heat a Swimming Pool?

The most efficient way to heat a swimming pool is to cover it with a solar blanket and use a gas pool heater.

Solar blankets prevent up to 95% of evaporation, while the heater keeps the trapped pool water as warm as you want it to be. You could also use an electric pool heater if it’s cheaper in your area.

Here’s what I suggest:

  • Use a solar blanket to prevent evaporation. I like the Sun2Solar Pool Cover, which is a 12 ml cover that retains up to 95% of the water in your pool. This blanket comes in 35 different sizes, saves your water bill, keeps your pool warmer, and can prevent excess chemical usage. The solar cover can also prevent algae.
  • Install a gas or electric pool heater. I recommend using a pool heater to increase the water’s temperature manually. Most pool heaters can increase the water’s temperature by up to 15 to 20 degrees Fahrenheit. You’ll want to maintain a steady temperature rather than letting it drop at night.
  • Get a liquid solar blanket or solar ball. A solar ball dispenses the same liquid found in a liquid solar blanket. Both options create a thin film that prevents evaporation and heat loss. I’ll dive further into both of them later in the article to help you decide which is the better option for your pool.

As you can see, heating your pool requires much more than direct sunlight. While the sun’s UV rays provide a much-needed temperature boost, several other factors play a role in the water’s temperature.

How Do You Heat a Pool in the Winter?

To heat your pool in the winter, follow these instructions:

  1. Keep the water moving during the coldest hours of the day and night. The plumbing can freeze if it gets too cold, which stops the pump from pulling water. A lack of water circulation lowers the temperature even more, preventing most of the chemicals from working. It can also stop the heater from doing anything.
  2. Use a pool heater to prevent the water from dipping below the desired temperature. Pool heaters are some of the most effective ways to heat a swimming pool during the winter. They rely on gas or electricity rather than ambient heat or direct sunlight. You can have a warm pool on a cold winter night.
  3. Put a winter cover or solar cover over the pool, depending on how often you use it. Solar covers and winter covers retain most of the heat from a pool heater. They also prevent plumbing freezes, chemical loss through evaporation, and more. Keep in mind that winter blankets aren’t as effective as solar blankets when it comes to heating a pool.

Heating a pool during the winter often costs a lot more than heating it during the summer. You’re constantly battling the frigid outdoor temperatures with gas or electricity.

Your utility bill can skyrocket if you don’t do it correctly.

Our best tip is to set the heater’s temperature to about 70 to 75 degrees Fahrenheit and let it rest there throughout the colder months.

Letting the temperature drop and increase with on and off heater usage will use more energy.

Is It Cheaper to Heat a Pool With Gas or Electric?

It’s cheaper to heat a pool with electricity because most utility companies charge less for electricity compared to gas.

However, you might have to use a lot of electricity to increase the pool’s temperature, so it’s worth discussing with your power provider before making the decision. Electric heaters typically cost more upfront, but they often save more down the road.

Gas and electricity prices range from place to place, so you might save more on one than the other.

However, most places charge more money for gas. Keep in mind that most electricity sources derive from gas-assisted plants. For example, many wind-power plants use gas to get started.

Using solar panels is the only way to power your pool’s electric heater in an eco-friendly way.

That being said, people often prefer gas heaters for their swimming pools for these three reasons:

  1. Not all cities allow people to use electric pool heaters because they demand so much energy and can cause grid issues (especially on days with high usage on the grid from neighbors and local businesses).
  2. Gas heaters work much quicker than electric heaters.
  3. Gas heaters are almost always cheaper than electric heaters upfront.

If you want a gas heater for your swimming pool, I recommend the Pentair Mastertemp 125K BTU.

This heater was a top seller during my time in the industry. It uses a membrane pad to adjust the temperature, set a schedule, and more.

The heater has an 82% efficiency rating, which is almost as high as it gets in the industry. It works for pools of up to 15,000 gallons.

Pro-tip: The Pentair Mastertemp 400K BTU is better for those with swimming pools over the aforementioned 15,000 gallons. It has the same footprint, efficiency, and lightweight construction. You’ll also receive the same multi-year Pentair warranty.

Do Solar Rings Work to Heat a Pool?

Solar rings work to heat a pool by preventing the water under the rings from evaporating. They also trap the UV rays under the surface, elevating the water’s temperature. Solar rings are excellent for people with pets or children that might fall into the water. They’re much safer than falling on a solar blanket.

Breaking Free Mediation recommends using solar rings because they’re easier to handle than a solar blanket.

You can remove and stack the rings, using less space and keeping your pool area much tidier. These rings use magnets to stick to one another, preventing them from floating apart.

Another reason so many people are making the switch to solar rings is that they break apart when someone steps on them.

Solar covers are slightly more efficient, but they wrap around anything that falls into the water. Furthermore, the prices are comparable.

The Solar Sun Rings are a great choice because each pack includes six 5-foot rings. Place them on the pool’s surface next to each other for the magnets to stay connected.

You can purchase them in bulk to save money and cover the gaps between the rings.

A fully-covered pool will retain up to 50% of the sun’s heat with these unique pool heating devices.

Will Black Garbage Bags Heat Your Pool?

Black garbage bags will work to heat your pool, but they bring phosphates and debris into the water. You’ll end up with lots of algae and a clogged filter.

Trash bags aren’t designed to handle constant corrosion from the UV rays and chlorine, so they’ll quickly waste away. The same issues apply to black tarps.

People often use black garbage bags because they’re inexpensive, easy to use, and extremely lightweight. Furthermore, black trash bags get hotter than any other color.

That being said, using a black trash bag to heat your pool is one of the biggest mistakes you can make as a pool owner.

Black trash bags are fragile compared to solar blankets and solar rings. They rip apart and deteriorate from the chlorine and sunlight.

Your pump will clog with bits of the trash bags, damaging the motor and impeller. You might have to replace the whole pump, which costs much more than a solar blanket.

Another reason you shouldn’t use black trash bags is that they can sink into the pool. They’re not designed to float once water gets on top of them.

On the other hand, solar blankets can have several gallons of water on top of them without sinking. They also prevent much more evaporation and are more durable.

The good news is that there are cheap ways to heat your pool without getting a heater. Read on to find the best solution without adding to your equipment pad.

What Is the Cheapest Way to Heat a Pool?

The cheapest way to heat a pool is to use a solar cover.

Solar covers prevent evaporation and retain the sun’s heat. You can combine them with a liquid solar cover to drastically reduce excess evaporation, improving the solar cover’s effects. These covers work better when they’re under direct sunlight for several hours daily.

Solar covers come in all shapes and sizes. I mentioned the Sun2Solar Solar Blanket earlier in the post. You’ll spend about 10% of what you would on a pool heater.

While you can’t directly control the pool’s temperature, there’s no denying the benefits of 95% evaporation reduction and heat retention.

Using a solar blanket not only saves money but also makes your pool last longer.

For example, your Intex pool will last longer with a solar cover because it prevents chemical loss and debris from getting into the pool.

Sharp sticks and rocks can destroy a vinyl liner, but an inexpensive solar blanket will keep most debris out of the water.

Pro-tip: Make sure you cover as much of the water as possible. Solar blankets are ineffective if there are too many gaps. You should point the cover’s bubbles toward the water to retain as much heat as you can. Some experts suggest getting a cover big enough to overlap the edges of the pool.

Do Solar Balls for Pools Work?

Solar balls work for pools by dispensing an evaporation preventative chemical.

Place the solar ball in the skimmer basket (or as directed by the manufacturer) and circulate the pump. The moving water pulls the chemicals through the pool, preventing the heat from leaving the water.

Solar balls are the next best solar heating method behind solar blankets.

The AquaPill Solar Pill is a perfect example of a top-notch solar ball. Place the ball in the skimmer basket and run the pump to slowly dispense the chemicals.

These solar balls are completely safe for people and pets to use while they’re in the water. Every Solar Pill lasts up to 30 days in a 12,000-gallon swimming pool.

People often choose solar balls over liquid solar blankets because they require less maintenance. However, both of them are equally as effective.

It’s up to you to decide which option is more efficient for your swimming pool.

Let’s move on to liquid solar blankets below.

What Is a Liquid Pool Blanket?

A liquid pool blanket is a chemical that prevents the water from evaporating. These liquid blankets create a thin, invisible layer on the surface. The sun’s heat goes through the barrier, but it can’t evaporate as quickly. The result is a warmer pool that can be up to 10 degrees Fahrenheit higher.

Liquid solar blankets are almost as useful as solar blankets. The invisible film is excellent at preventing evaporation, which also saves your pool’s chemicals. Make sure the manufacturer encourages swimming after using it if you want to swim right away.

I always used the Natural Chemistry Cover-Free Liquid Solar Cover in our pools. Each bottle prevents up to 85% of evaporation and 70% of heat loss.

This weekly treatment is great for pools up to 20,000 gallons. Every bottle includes about eight weeks’ worth of 4-oz treatments, though you can increase the dosage if you have a pool that’s bigger than 20,000 gallons.