Do Solar Pool Covers Cause Algae Growth?

Many pool owners have taken their solar covers off their pool, only to find that their water has turned green underneath. So, great news: the solar cover works. Unfortunately, a consequence of warm water is algae growth. So why is it that some people swear by solar covers, and others have to contend with green algae?

Solar pool covers can indirectly cause algae to grow due to fostering the warm conditions that allow it to thrive, so keeping your water chemistry balanced is more important than ever before. That said, solar covers can keep debris and rainwater out, keeping your filters clean and keeping the pool chemistry from going off balance. It’s a double-edged sword type of situation that you need to monitor closely.

In this article, I will discuss the advantages and disadvantages of using a solar pool cover with regards to causing or preventing algae growth. Then you can decide for yourself if you think it is worth the hassle or not.

What causes algae to grow in the pool?

Algae can bloom in your pool if the conditions are right. Some factors that can cause this are:

Solar pool covers, and by extension liquid solar covers, can dramatically impact the first point: increased water temperature. But since that is the point of using a solar cover in the first place, we need to address the other points in the list to prevent algae blooms from appearing.

Stagnant water is an easy problem to solve; simply keep your pool pump running even while the solar cover is on to ensure there is proper circulation and that the water is getting filtered.

With regards to low chlorine levels and high acidity, a solar pool cover can actually help you with these problems. By covering your pool up, you keep rainwater out which is acidic. Also, solar covers keep wind out and absorb much of the UV rays from the sun which prevents chlorine from being destroyed or evaporated.

On the last point, if you get rid of algae’s food source (phospate) using a phosphate remover, then it will starve until it dies. Alternatively, you can shock your pool or use an algaecide to kill all types of algae and get your pool water sparkly clean again.

Is a solar pool cover responsible for algae?

As mentioned, solar pool covers can indirectly lead to algae in the pool due to warmer water temperatures, but it also has some positive qualities that can prevent algae growth.

That said, there are more factors to consider. The quality of your solar pool cover and consistent maintenance on your part is necessary to ensure algae stays away, especially if you keep it on most days.

For instance, algae can grow on the solar pool cover itself if it is not being rinsed on a bi-weekly basis. Also, since debris can accumulate on the pool cover, some pool owners accidentally allow the debris to drop into the pool as they try to remove the cover.

Some pool owners are cutting it too close with the size of their solar cover. Ideally, it should be at least a couple of inches longer than the edge of the pool on all sides. Any exposed gaps can let debris and rainwater in, which can increase the chances of algae growth.

How to prevent algae growth with a solar cover on

Algae growth is a concern for pool owners whether you have a pool cover or not, but the extra warmth that pool covers can foster an environment for algae to thrive.

To prevent algae spore growth when using a solar blanket, there are some matters you can take into your own hands:

  • Ensure the pool surface is covered at all times. Check for any gaps that may allow water or debris to find their way in.
  • Look for any tears or holes in the solar blanket. If there was some rough weather recently, it is possible a tear has opened. If the tear is small, you can still patch it up using a solar blanket repair kit before it gets larger.
  • Regularly vacuum the pool and clear off any debris on the solar cover.
  • Check the pool’s pH and make sure it stays within 7.2 and 7.6 and that the free chlorine is between 1-3 ppm. The solar cover should be excellent at keeping the pool’s pH and chemical levels the same, but you should still check occasionally.
  • Make sure the pool pump is running while the solar cover is on. This ensures all water is being filtered and that the warm water is being evenly distributed instead of just lingering at the surface.
  • Skim the surface of your pool regularly.
  • Be prepared to use algaecide or to shock your pool if you notice the water is turning green.

How to clean algae from your pool cover

Don’t focus entirely on keeping your pool algae clean and neglecting your solar cover. It can also have algae growing on them too.

If your pool’s chlorine levels are too low or you haven’t used any algaecide, algae can start to grow on the cover itself. Most solar covers aren’t algae resistant, so you should be rinsing them at least bi-weekly to sanitize them.

Should you find algae growing on your solar cover, here are the steps you should take to clean it:

  • Take the solar cover off from your pool and rinse it thoroughly with a garden hose.
  • Dry the cover with a towel.
  • Use a water testing kit on your pool. Make sure the pool’s chlorine, cyanuric acid, pH, alkalinity, and hardness are all balanced.
  • Place the solar cover back on your pool.

Solar blankets are your pool’s first line of defense against algae blooms when used properly. However, it is not a set-it-and-forget-it piece of equipment. You still need to perform maintenance on it and your pool.

Failure to check on your pool and your solar cover will leave you with a green pool that you need to put in more work to clean up than if you had just kept up with maintenance in the first place