Swimming pools can turn green due to the growth of algae. Algae thrive in warm, humid environments and can grow quickly in a pool that has poor circulation, high levels of organic matter, and low levels of chlorine. Algae can also grow faster in shaded areas of the pool, where sunlight is limited, which slows down the natural disinfection process. To prevent a green pool, it's important to maintain proper chemical levels, regularly shock the pool, and ensure that there's adequate circulation and filtration. Regular cleaning and vacuuming can also help to remove organic matter before it has a chance to fuel algae growth. Read more about alage here; Understanding Algae.

To keep a swimming pool clear and clean, it's important to maintain proper pool chemistry, which involves balancing the levels of various chemicals in the water. Here are the key factors to consider:

Chlorine: Chlorine is the most important chemical for keeping a pool clear, as it kills bacteria, algae, and other contaminants. The recommended range is 1-3 ppm (parts per million).
pH: The pH level of the water should be between 7.2-7.8 to ensure that the chlorine is effective and that the water is safe and comfortable for swimming.
Alkalinity: Total alkalinity helps to stabilize the pH levels and should be between 80-120 ppm.
Calcium hardness: Calcium hardness helps to prevent damage to the pool's surface and equipment, and should be between 200-400 ppm.
Cyanuric Acid: Cyanuric acid helps to stabilize chlorine levels, particularly in outdoor pools, and should be between 30-50 ppm.

It's important to regularly test the pool water and adjust the chemical levels as needed to maintain proper pool chemistry. Over-chlorination or imbalanced chemical levels can cause skin irritation, damage to pool surfaces, or even corrosion to equipment. A pool professional can help you determine the specific chemical levels needed for your pool based on factors such as size, location, and usage. To find out more about how to care for a green pool, check out this article by Orenda Technologies, Green Pool Clean Up.

Why is my pool green?