Do Solar Pool Covers Cause Algae?

Do Solar Pool Covers Cause Algae?

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Over time algae will become resistant to normal levels of chlorine. If you do not take care of the condition of your pool, algae will breed rapidly and become a real nuisance. Conditions that promote algae growth include a food source (phosphates), warm water, and low chlorine levels. However, there have been many ongoing debates about pool covers facilitating algae growth.

Can we prove that solar pool covers actually cause algae? Simply having a solar pool cover will not cause algae growth. However, having the cover on will make the water warm, which can accelerate the growth of already present algae in the pool. You will have to change the conditions to prevent algae growth, and the best solution for this is to use algae starve products. Algae starve products eliminate phosphate build-up, and the algae will starve to death.

This article explains how pool covers contribute to rapid algae growth, provides tips on removing different types of algae from the pool, and provides answers to related questions.

How Do Pool Covers Promote Algae Growth?

If you already have phosphates and low chlorine in your pool, adding a solar pool cover will make the existing algae thrive. So, while a cover will not turn the pool green, it will warm your water by over 10 degrees, accelerating algae growth.

You must get the water balance in your pool right before placing the cover on the pool. Professionals usually take a water sample to understand the water conditions within the pool, and then they work out how to adjust the conditions for you.  

If you want to do it yourself, the first step is getting algae starve. It will get rid of all the phosphates, and the algae will starve.

Filter the pool for 12-24 hours to remove all the spores from the water. It is a great idea to wash the filter after using it to remove trapped algae spores. If any spores remain in the filter, the problem may reoccur.

If the algae problem is severe, you will have to visit the pool shop. You will need professional advice and somebody who can perform super chlorination. The concentration and quantities of chemicals used need to be accurate. Ensure that you remove the cover and do not put it back onto the pool until the chemicals have returned the pool water to the required standard.

If you notice that the pool water is warm, you may want to consider getting a non-heating pool cover. It will stop evaporation, and will not heat the water like a traditional solar pool cover.

Effective Ways to Get Rid of Pool Algae

You may not have lily pads floating in the water, but microscopic algae are still present. Do not fill the pool with chlorine but also do not algae the opportunity to spread. Whereas some types are resistant to chlorine, there are others ways to control algae problems. The method you choose will depend on the color of the algae.

Pink Algae

Pink slime is one of the bacteria that grow in swimming pools, especially in PVC pipes. They tend to resist pool chemicals, making it difficult to remove them. However, you can remove them manually. While doing so, ensure that you check the inside of the filter system.

Black Algae

When the black algae multiply, you may notice little black spots on the surface of the pool’s concrete surface. This is because black algae spread across the surface of a swimming pool by rooting themselves in the concrete. You may even notice it more in areas where the water circulation is limited. This type of algae is not algae but rather a type of cyanobacteria. This is an interesting bacteria type because cyanobacteria produce their own food.

You need to be quite persistent with cleaning black algae spots. Use a stainless-steel brush to scrub the affected area. Once you start noticing spots, scrub them daily until they start to fade. In most cases, you can eliminate them over time, but in some instances, you may not be able to remove them entirely but rather manage the situation. This is why it’s essential to scrub black algae spots immediately, as soon as they first appear.

Green Algae

Green algae are also known as Chlorophyta and get their color from chlorophyll. When the water circulation in your pool is poor, green algae will start to form, making the water cloudy and murky. This appearance is both unhealthy and unsightly.

Thankfully, they are the easiest to remove. However, if you neglect green algae, the floor and stairways will become slippery, potentially causing slipping and falling accidents. You can add chlorine or algaecide like this to kill green algae. Ensure the filtration system is on during treatment.

Having the filter on will clear the water and eliminate dead algae. The chlorine concentration should be at least 1ppm.

Mustard Algae

Mustard algae are probably one of the most challenging types of algae to eliminate. This is because their presence is hard to detect. If your pool is blue, the mustard algae may even appear green in color. Most people think that their pool merely has a bit of dirt or pollen on the sides when in fact, it’s mustard algae! How can you tell if it’s dirt and pollen or algae? Well, if you brush mustard algae from the side of the pool, the algae will gravitate back to the wall’s surface. When you brush pollen and dirt from the wall, the particles will drop to the floor of the pool.

When mustard algae are involved, the treatment process can be tricky. These algae are resistant to chlorine treatments, and they find innovative ways to get into your pool, such as through contaminated swimwear and pool accessories, and can even end up in your pool when it’s windy or raining. As a result, most treatment methods involve a chlorine accelerator or algaecide.

What is a Solar Pool Cover?

A solar pool cover, also referred to as a solar blanket, is a large sheet of plastic that looks like bubble wrap – it is placed on top of the pool. When purchasing this cover, you will have many options to choose from. The market presents many sizes, thicknesses, and colors.

It has a strong, flat layer on one side and bubbles on the other side. The bubbles act as an insulator to stop the transfer of heat from the pool. The primary purpose of the cover is to minimize the amount of heat lost through evaporation, saving heating costs significantly.

How does a Solar Pool Cover Work?

A pool cover works mainly in three ways:

  1. It floats on the pool’s surface and allows sun rays to enter the pool and heat the water.
  2. As the water is not exposed to air, evaporation is reduced. One way heat is lost from the water is through evaporation.
  3. It acts as a giant blanket and insulates the pool, especially at night and during windy conditions.

Advantages and Disadvantages of Solar Pool Covers

Having a solar cover comes with advantages and disadvantages. The benefits you derive from a solar pool cover depend on how you use the cover and the extent of use. Below are some of the pros and cons:


  1. A solar cover allows the rays of the sun to heat the water inside the pool.
  2. It helps retain the heat by insulating the water from the air above.
  3. You save water as there is less evaporation as it covers the entire pool.
  4. You will use fewer chemicals as the cover blocks UV rays.
  5. It is eco-friendly, as you will use less electricity.


  1. The initial cost is high for both the cover and roller.
  2. There is extra work of placing the cover on and off.
  3. The cover does not last for long, and it needs changing over time.

Related Questions

How long do solar covers last?

Over time, your solar cover will slowly deteriorate. You will have to replace it once the bubbles begin to fall off and it starts to flake. Most of the solar covers last for four years.

Are Clear Solar Covers Better?

Clear solar covers allow more light energy to penetrate your pool. Clear solar covers may absorb less heat, but the heat provided may be more than colored covers.

See Also:
Can You Use Bubble Wrap as a Solar Pool Cover?
What is the Purpose of a Solar Pool Cover?
Can You Cut a Solar Pool Cover?

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