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Pool Algae Guide

Algae are a common problem in swimming pools. Algae will grow in any pool if the conditions for their growth are present. These single-celled plants are often found on the steps and corners of swimming pools. They are the slimy growths with a furry appearance you sometimes find in parts of the pool where there is low circulation.

Algae can be found in a range of natural environments, especially in plant debris. Their spores may be transported into a pool by wind, plant materials that fall into the water, and contaminated swimwear. However, even if algae spores are present in a pool, algae will not grow until they have the right conditions.

Conditions that favor algae growth

Algal growth in a swimming pool is supported by:

  • Sunlight: Being an aquatic green plant, algae need sunlight to survive. Warm areas of the pool with regular exposure to sunlight are favored by algae.

  • Poor circulation: Algae prefer those areas of the pool where the water is still or water movement is slow. This is why they are often found on the steps.

  • Poor sanitation: Swimming pools which are insufficiently sanitized are more vulnerable to algae. This is also true for pools with inadequate filtration.

  • Chemical imbalance: If pool water pH, calcium, and cyanuric acid are not at the right levels, algae can take hold.

The different kinds of swimming pool algae

There are several thousand kinds of algae, but the algae most commonly found in swimming pools can be classified as:

  • Green algae: This is the most common kind of pool algae. Green algae not only grow on pool walls and steps; they will also float in the water. Once the first signs of green algae appear in a pool, they can spread rapidly and make the water cloudy within 24 hours.

  • Yellow algae: These normally grow in the shaded areas of the pool, mainly on walls. Also known as “mustard algae,” they do not spread as fast as green algae. However, because yellow algae grow in sheets, they can harder to get rid of than green algae.

  • Black or blue-green algae: This kind of algae grows in ponds, lakes, and the ocean. But they can be transported into swimming pools on swimwear that has recently been in the ocean. Black algae is the hardest kind of algae to get rid of. Unlike other algae, it does not use slime as a protective covering. Instead, it buries itself deep inside pool surfaces, making it very hard to kill.

  • Pink algae: Strictly speaking, this is not algae but bacteria. It manifests as a slimy growth with pink and orange tones. Pink algae is mostly found along the pool water line and is also attracted to PVC surfaces in the pool. It often occurs along with white water mold, a fungus.

How to prevent algae

As already stated, the best way to deal with algae is to prevent it. You can do this by:

  • Along with regular skimming, use a vacuum to remove debris from the pool.

  • Designing an efficient and up-to-date system for ensuring proper chemical balance of the water.

  • Making sure pool chemical balance is methodically checked on a schedule.

  • Ensuring the pool is adequately shocked on a weekly basis to prevent organisms from growing in it.

  • Using a pool brush that will not damage pool surfaces, as this can make it easier for algae to grow.

  • Always having the right pool stabilizers in stock and applying them at the first sign of trouble.

  • Encouraging swimmers to wash their swimwear and shower before entering the pool.

Finally, you should talk to a pool maintenance expert and have them inspect your pool to identify any issues that may predispose the pool to algae.

Thank you to PinnaclePMC for providing help with this content. PinnaclePMC is located in the heart of the South Bay; their office has over 30 Years of property management and real estate experience.

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