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What is The Perfect Pool Temperature?

By Matt Giovanisci | Updated: June 18, 2019

Few pool topics are debated as heatedly (pun fully intended) as pool temperature. Your neighbors, your local pool store, that one guy at work who thinks he knows everything about everything, the countless pool articles on the internet—they all have opinions, and most of them are at odds with each other. So who’s right?

We are, of course! In all seriousness, we’ve researched it to try to answer the question of perfect pool temperature once and for all. Short version? There’s not just one answer. How warm or cool you keep your pool, and how you do it, depends on several factors. It’s just a matter of knowing which of those factors apply to you so you can make the best choice.

Why is Pool Temperature Important?

Have you ever jumped into a nice, cool swimming pool on a super-hot day? It’s either refreshing or a nightmarish shock to your system. Or maybe you got into your pool and felt like you were taking a warm bath on a hot day. That’s no fun either.

In general, the most common pool temperature for a residential pool used for leisure is between 78°F and 82°F (26°C and 28°C).

But it’s important to know that some temperatures can be dangerous for certain at-risk groups of people, and can make your pool vulnerable to contaminants. And other temperatures are conducive to more athletic activities.

It all depends on who uses your pool, and for what purposes.

Leisure, Lessons, and Lots of Fun

If your pool is a gathering place for the whole family and lots of friends during the summer, you’ll need to take swimmers’ ages into account.

And is everyone just floating around for fun? Or are a few people using your pool for fitness or other efforts? It all makes a difference.

Kids and Swimming Lessons

The American Academy of Pediatrics recommends swimming lessons for kids starting at the age of four. and the Red Cross recommends a pool temperature of at least 84°F (29°C) to conduct swim lessons for children.

This is to keep their bodies comfortable in a new environment, to keep their muscles warm and loose, and to prevent any breathing difficulties that can arise from too-cold water.

While you may not be offering formal swimming lessons in your pool, if you’re trying to teach a young child to swim, consider raising the pool temperature, at least while this activity is taking place.

Important: Teaching a child to swim does not prevent drowning. When you have kids in or near the pool area, make sure they’re supervised at all times. Consider taking precautions to prevent tragedy, and perhaps investing in a couple of types of pool alarms for added safety.

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Senior Health and Safety

As we age, our bodies become less tolerant of drastic temperature changes, and more vulnerable to both heat and cold. This is particularly true in swimming pools where too-cold or too-warm water can not only be uncomfortable for seniors, but detrimental to their health.

When the seniors in your life are going to use your pool for leisure, consider raising the temperature to somewhere between 86°F and 88°F (30°C and 31°C).

Water exercises can be particularly helpful for those with arthritis. The water’s buoyancy means less stress on joints, and little risk of falling while exercising.

If anyone with arthritis—senior or not—will be using your pool, they’ll be most comfortable in temperatures between 84°F and 88°F (29°C and 31°C). If they have limited function due to arthritis, they’ll do better in even higher temperatures, somewhere between 86°F and 90°F (30°C and 32°C).

Health and Fitness Benefits

You don’t have to be a senior to use the pool for fitness. Swimming is excellent full-body exercise, and has several benefits:

For swimming and water aerobics, the recommended temperature is the standard range of 78°F to 82°F (26°C to 28°C). So you can get a lot of health benefits without having to adjust the temperature much at all.

Before You Start Adjusting and Readjusting Pool Temperature

If you normally keep your pool around 78°F (26°C), it can put a bit of strain on your pool heater (and your energy bill) to bring the water up to 90°F (32°C), or even just 84°F (29°C) to accommodate a child, a senior guest, or someone with arthritis.

If such a guest is only going to use your pool occasionally, heating it up to the appropriate temperature isn’t really cost-effective. It will also wreak havoc with your water chemistry.

If someone in your household is older, if anyone is living with arthritis, or you have senior guests on a regular basis, you may want to consider getting a hot tub instead of raising and lowering your pool temperature.

Hot tub temperature will always be somewhere between 98.6°F (37°C) and the maximum safe temperature, 104°F (40°C). It also offers that same buoyancy for low-impact exercise, though it may need to be performed sitting down rather than standing. But sitting in a nice, warm, bubbly hot tub isn’t really a sacrifice, is it?

Controlled Pool Temperature Benefits

In addition to protecting swimmers, keeping your pool temperature steady and within the right range can also protect the pool itself.

Algae and Bacteria Control

You’re constantly battling pool water contaminants, and for the most part, you keep them under control with chlorine or another sanitizer, and with filtration. But let the pool temperature get too high, and you’re practically laying out the welcome mat for algae and bacteria.

When your pool water heats up to around the 85°F (29°C) mark, bacteria and algae get nice and comfy, and start reproducing at exponential rates. Keeping your pool below that mark won’t get rid of algae and bacteria completely, but will make it more difficult for them to bloom and grow and become a problem.

If you do raise the heat in your pool to accommodate guests, shock it more often to keep algae, bacteria, and other contaminants at bay. If that’s not a concern, then try to cool the pool down to prevent an algae bloom.

Balanced Water

With that warmer water in your pool making it easier for algae and bacteria to gain a foothold, the chlorine or other sanitizer in your pool is going to have to work much harder to kill them. This means the sanitizer will become depleted more quickly, and your pool chemistry will be out of whack.

It also means you’ll have to add sanitizer more often, so a bonus to keeping your pool temperature within a good range is that you’ll save money on chemicals.

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Keep Swimmers Comfortable

Aside from maintaining certain temperatures to keep at-risk swimmers safe, you want everyone who swims in your pool to be comfortable. Too cold or too warm, and no one’s going to enjoy it. And then what’s the point of having a pool?

Set your pool heater’s thermostat to a temperature between 78°F and 82°F (26°C and 28°C) to keep the majority of swimmers comfortable. Maybe a little cooler if you’re in an area with very hot summers, or a little warmer if you live in a milder climate.

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How to Measure Pool Temperature

All pool heaters have built-in thermostats to let you set and maintain the pool temperature you decide on. But just like the thermostat in your home may not accurately display the temperature from the room farthest away from it, the heater thermostat may not be completely accurate, either.

To get an accurate pool temperature reading, supplement the thermostat with a pool thermometer. You have three types to choose from: analog, digital, and infrared. We recommend digital for accuracy and cost-effectiveness.

Analog thermometers can be difficult to read accurately, and infrared thermometers are a little on the expensive side for residential use. Unless you just like pointing what’s basically a laser gun at your pool while you shout, “Pew! Pew!” We won’t judge.

How to Control Pool Temperature

Knowing the perfect pool temperature is only half the battle. Now you need to know how to keep it steady.

Choose an Efficient Pool Heater

You have three options to heat your pool.

You can rely on the sun, but this is really winging it, and you’ll have no way to control the pool temperature. Plus, the water will usually be a lot cooler than may be comfortable in certain regions or at certain times of the year. However, getting a solar pool cover can help you take advantage of this free heat source. And we recommend using a solar cover even if you have a pool heater to help retain heat.

A gas pool heater can be a good, economical option if you have natural gas available. If not, you can choose a heat pump.

Finally, you can still use the sun, but in a much more focused and efficient way with a solar pool heater. If you have the space on your roof, it’s definitely worth looking into.

Take a thorough look at all your options before making a decision.

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Get a Pool Heater With a Digital Thermostat

Any heater will have a thermostat, but the ones with digital thermostats are more accurate and easier to use. And the thermostats controlled by microprocessors are even more reliable, albeit more expensive. But you’ll make up for it in energy bill savings.

Save Money and Energy

Heating a pool is an expense along with pool chemicals and other maintenance tools and equipment. While you want to keep your pool temperature on an even keel, and keep your pool comfortable for everyone, you also don’t want to run up your energy bills.

A few heating tips will help keep things comfortable in the pool and in your bank account.

Turn the Temperature Down

If you don’t have to worry about maintaining a higher temperature for kids or seniors, consider dropping the pool temperature by a degree or two. That’s really all it takes to save money:

The energy consumption for each degree rise in temperature will cost 10% to 30% more in energy costs, depending on your location. In warmer climates, this percentage is higher because of the relatively low cost of heating a pool at 78ºF. – Energy.gov

Turn the Pool Heater Off

Going on vacation? There’s no need to keep your pool heated while you’re gone. Turn the thermostat down, or better yet, off to save both money and energy.

But won’t it take more money and energy to get the pool temperature back up when you return? It will take some energy and money, but not nearly as much as it would take to keep the pool heater running while you’re not even using the pool.

Use a Solar Pool Cover During the Day

Yet one more way to harness the power of the sun. If you’re going to be out of the pool for a while, float a solar pool cover or a solar blanket on it to both heat the water and retain that heat, depending on the type of cover you use.

If you feel a total-pool cover is too cumbersome to use frequently, consider getting a solar cover reel to make things easier. Or try using solar rings instead. Easy to deploy, easy to pick up and put away.

Solar Rings For Pool Heating

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Use a Pool Cover at Night

Both your pool heater and the sun warm up the water during the day. Hold onto some of that heat by covering your pool at night. The cover will trap some of the heat, and when you remove it in the morning, your heater won’t have to work as hard to get it up to the set pool temperature.

If you’d rather not completely cover the pool when you’re just going to use it the next day, put a solar blanket on the water. It won’t keep as much heat in as a regular cover would, but it will keep some.

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Maintain Your Pool Heater

After you’ve spent all that money on an efficient pool heater, it would be a shame to let it fall into disrepair. Just like all your other pool equipment, it needs regular maintenance. Keep it running well, and it’ll last a lot longer, which will save you the money of having to replace it too soon.

Above Ground Pool Temperature

You may be wondering how to set and maintain the pool temperature if you have an above ground pool. It’s very complicated. Are you ready?

There’s no difference.

All the same tips and tactics you’d use for an inground pool also apply to above ground pools. Get a good above ground pool heater, keep it in good condition, use a pool cover, and you’ll be fine.

Not Too Hot, Not Too Cold, Juuuust Right

Only you can determine the perfect pool temperature for you. Whether you have kids and seniors using the pool, or it’s just a source of fun and relaxation, once you’ve decided on your goal temperature, it’s just a matter of maintaining it.

Just remember to keep health and safety concerns in mind, and then everyone will be able to enjoy fun in the sun right in your own back yard pool.

Happy Swimming!

Matt Giovanisci is the founder of Swim University® and has been in the pool and spa industry since 1995. Since then, his mission is to make pool and hot tub care easy for everyone. And each year, he continues to help more people with water chemistry, cleaning, and troubleshooting.
A Cheat Sheet For Perfectly Balanced Pool Water and Crystal Clear Swimming
Download this FREE printable cheat sheet to keep your pool clean and clear without any fuss. You’ll never worry about your pool again with this easy-to-use guide.
Click Here For The FREE Cheat Sheet