Why does my pool turn green or blue?

Experiencing a colour change in your pool water can be concerning. A green colour typically signifies algae growth, while a blue or green tint might indicate metal presence in the water. Identifying the cause is the first step in restoring the pool's clear and healthy water.

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What Causes Green Algae?

The green colour in pool water is most commonly caused by algae growth. This usually occurs due to low chlorine levels, which are insufficient to prevent algae or a pH imbalance that reduces the effectiveness of chlorine. To treat the problem, you can increase the chlorine level in the pool to effectively kill the algae. It’s also worth testing and adjusting the pH level of the water to ensure the chlorine works effectively. Use an algaecide and regularly brush and vacuum the pool to remove algae.

What Causes Blue Algae?

A blue or green tint in pool water, especially in pools with copper plumbing or heaters, is often due to low pH levels causing copper leaching into the water. This can occur in salt water pools or those treated with certain algaecides that contain copper. Correct the pH level of the water to stop further copper leaching, and use a metal sequestrant to bind with the copper, preventing it from staining the pool surfaces and water. Regular testing of pH and metal levels in the pool can help prevent recurrence.

Preventive Measures to Avoid Algae Growth

Regular maintenance, including consistent chemical balancing and equipment checks, is key in preventing both algae growth and metal leaching. Keeping a close eye on chlorine levels, pH balance, and overall water chemistry can go a long way in maintaining clear and healthy pool water. Working with professional pool cleaners will also help keep your pool in good condition and prevent algae from forming.

Addressing these issues involves correcting the chemical imbalance and using appropriate treatments like metal sequestrants. Regular monitoring and maintenance of pool water chemistry and equipment are essential in preventing these colour changes and maintaining a clean, inviting swimming environment.