Green Pool: Top Reasons Why Pools Turn Green

Why Swimming Pools Turn Green

Have you ever wondered why swimming pool water turns green? It’s not a pleasant sight, and it can also pose health risks for you and your family. We will explain the main causes of green pool water and how to prevent and fix it.

Table of Contents

• Top Reasons for Green Pools
• The Main Culprit: Algae
• Different Types of Algae
• How to Prevent Algae Growth
• How to Fix a Green Pool
• Conclusion

Top Reasons for Green Pools

Circulation is the life blood of all pool systems, and is one of the main reason why a swimming pool will turn green. Keeping the water in the pool circulating freely should be your number one priority, and we have provided some reasons why a pool turns green and some which prevent pool water from circulating properly.

Here are the top reasons why a pool turns green:

• The pool water is old
• The pool has an improper chemical balance
• The pool gets an excessive amount of debris (can effect water circulation)
• The pool filter is dirty and clogged (can effect water circulation)
• The skimmer or pot baskets are clogged (can effect water circulation)

There is poor water flow due to:

• clogged or poorly maintained pool vacuum (can effect water circulation)
• bad infloors (popup heads) (can effect water circulation)
• bad gears on infloor cleaning system, (can effect water circulation)

The Main Culprit: Algae

The most common reason for green pool water is algae growth. Algae are microscopic plants that thrive in warm, sunny and nutrient-rich water. They can multiply quickly and form a slimy layer on the pool surface and walls. Algae can also clog your filter system and reduce the effectiveness of chlorine.

Different Types of Algae

There are different types of algae that can affect a pool, such as green algae, yellow algae and black algae. Green algae are the most common and easiest to treat. They give your pool water a greenish hue and make it cloudy. Yellow algae are more resistant to chlorine and can form mustard-colored patches on the pool walls. Black algae are the hardest to get rid of, as they have roots that penetrate the pool surface and form dark spots.

How to Prevent Algae Growth

The best way to prevent algae growth is to maintain a proper chemical balance in the pool water. The pool water should be tested regularly using a test kit or strips, or by taking a sample to a pool store for analysis.

The main parameters to check for are:

• Chlorine level: Chlorine is the primary sanitizer that kills algae and bacteria in a pool. The free chlorine level is best kept between 2 and 4 parts per million (ppm). If it drops below this range, add more chlorine to the pool using shock or tablets. Monitor the cyanuric acid (CYA) level, which is a stabilizer that protects chlorine from sunlight degradation. The CYA level should be between 30 and 50 ppm. If it’s too high, it can reduce the effectiveness of chlorine and you may need to partially drain and refill the pool with fresh water.
• pH level: pH is a measure of how acidic or basic the pool water is. Keep the pH level between 7.4 and 7.6, which is the ideal range for chlorine to work and for your eyes and skin comfort. If the pH level is too high (above 8), chlorine becomes less active and algae can grow faster. You can lower your pH level by adding acid to the pool, such as muriatic acid or sodium bisulfate.
• Phosphate level: Phosphates are nutrients that feed algae and can come from sources such as fertilizer runoff, rainwater, leaves, dirt, sweat and cosmetics. Keep the phosphate level below 100 parts per billion (ppb). If it’s too high, use a phosphate remover product to reduce it.

Besides maintaining a proper chemical balance, run the filter system for at least 8 hours a day to remove algae and other contaminants from the water. For areas with hotter summers a good rule of thumb is for every 10 degrees of temperature over 80 degrees, the equipment should run for an extra hour. So 90 degrees outside would mean 9 hours of equipment run time and 100 degrees would be 10 hours of equipment run time. You should also clean the filter regularly (at least every 6 months) and backwash between cleanings if needed. Additionally, brush the pool walls and floor at least once a week to prevent algae from sticking to them.

How to Fix Green Pool Water

If your pool water is already green, there is no need to panic.

You can fix it by following these steps:

1. Test your pool water and adjust the chemical levels as needed.
2. Shock the pool with a high dose of chlorine (10 to 20 ppm) to kill the algae, by using a liquid chlorine or granular shock treatment. Make sure to dissolve the granules in a bucket of water before adding them to the pool.
3. Brush the pool walls and floor vigorously to dislodge any algae.
4. Run the filter system continuously until the water clears up. You may need to backwash or clean your filter several times during this process.
5. Vacuum any dead algae or debris from the bottom of the pool.
6. Test the pool water again and rebalance the chemicals if needed.

Conclusion

Green pool water is not only unsightly but also unhealthy. It’s caused by algae growth due to low chlorine levels, high pH levels, high phosphate levels, organic matter and/or poor filtration. You can prevent algae growth by keeping the pool water balanced and clean. You can fix green pool water by shocking the pool with chlorine, brushing the pool walls and floor, running the filter system and vacuuming the pool.

We hope this has helped you understand why swimming pools turn green and how to deal with it.