Will a Black Pool Cover Heat the Water?

If you are sensitive to the cold and feel that your pool is a bit on the chillier side for comfortable swimming, you may want to look at ways to heat it up. The most obvious solution is a pool heater, but they are expensive. A much cheaper alternative is to use a pool cover.

Most people simply cover up their pool with a tarp when not in use. Their primary goal in this case is to keep debris out and keep evaporation to a minimum, but the latter also results in the pool being warmer whether that was their intention or not.

Pool covers can make pools warmer, and a solar cover is specifically designed to trap heat. It can do all the other things a pool cover does as well, but will heat up your pool by as much as 10-15°F if your pool has a few consecutive days of sun exposure. You can use it alongside a pool heater to warm up your pool considerably faster.

If you want your pool to heat up quicker, consider using a black pool cover. Black pool covers absorb more sunlight than any other color which results in your pool being warmer. It won’t work miracles – you can’t expect to heat up your pool in the winter with it – but it’s a nice little tweak you can make for better results.

Keep reading on to learn how exactly pool covers can warm up your pool, why a black pool cover specifically can lead to better results, and other ways you can keep your pool warm.

Why should you use a pool cover?

If you are someone who really wants to use the pool more often but finds it slightly on the chilly side, it can ruin the experience for you.

A pool cover can help make the pool just a bit warmer so that when you finally do swim, it can be a comfortable experience.

Essentially, it’s all about start-up temperature. During warm days, your pool water will get warmed up by the sunlight. However, overnight it will lose all of that heat and the next morning it will be cold again. You don’t want to wait hours just for the pool to warm up, do you?

By covering up your pool at night, it can retain some of the heat that it absorbed from earlier in the day, so that the next morning it is still warmer than if you had left it uncovered.

The difference in temperature between a covered pool and an uncovered pool can be as much as 10-15°F. For someone who is sensitive to the cold, a 75°F pool will feel considerably more comfortable to swim in than a 65°F one.

How do pool covers keep your pool warm?

First off, any pool cover will keep your pool warmer, not just a black one. A black pool cover will simply be the most effective at it. But how does this work in the first place?

When your pool is covered up, it keeps air and wind from coming into contact with your pool. When wind moves across water, it carries away water vapor which dries the air around it. This leads to higher evaporation rates. What does evaporation have to do with keeping your pool warm?

In layman’s terms, when water evaporates, it cools its surroundings. You can read the more scientific explanation here. A pool cover will prevent most of the air from reaching your pool water and reduces evaporation by as much as 95%. Therefore, by keeping evaporation to a minimum, your pool will be considerably warmer.

Furthermore, a pool cover can literally just trap heat. When we go to sleep, we cover ourselves up in a blanket to keep warm. The blanket doesn’t generate any heat, but it helps us retain heat. Well you can do the same thing with your pool by covering it up with a pool blanket at night, and you will have a much warmer pool in the morning.

How does a black pool cover specifically heat the water?

So if any pool cover has a warming effect on the pool, what’s so special about a black pool cover?

A black pool cover retains heat better because black surfaces absorb light more than any other color. On the other end of the spectrum, white surfaces can reflect light, making it the coolest option.

Take a look at this video below to see a real-world example of this taking effect.

In the video, the hood of the black car measured 160°F (71°C), whereas the hood of the white car measured only 112°F (44°C), a nearly 50 degree difference between these two extremes.

The difference is less pronounced between black and other colors, but black still wins out.

You can even test this out yourself. Try wearing a black T-shirt on a bright and sunny day and compare how that feels when you wear a white T-shirt, or any other color T-shirt. The black T-shirt should feel the warmest compared to the rest.

So when we apply this logic to a black pool cover, it will absorb the greatest amount of light which turns into heat. This results in your pool getting warmer on a sunny day.

The black hose trick

In a similar vein, you can also increase your water temperature using what is commonly referred to as the “black hose trick.”

This is a simple and clever way to warm up your pool water without much effort or expense. All you need is to purchase a black garden hose and attach it to the outside water spigot.

Now, leave the hose in direct sunlight, preferably in its coil shape to increase the surface area that the sun can shine on. You can also just lay the black hose over your black pool cover to help with heating it up.

Anyways, the goal is to allow the black hose to absorb as much light as possible and get really warm. Then any water that flows through it will immediately come out warm.

This is great for when you want to refill your pool and want to heat it up a bit. If you live in a sunny climate such as Texas, this is a great way to take advantage of solar energy to heat your water.