Pool stains can make a swimming pool look dirty and uninviting. Understanding what causes these stains helps pool owners keep their water clear and their surfaces clean. Stains come from different sources, including minerals, organic matter, and chemical imbalances. This article explains the main causes of pool stains and how to prevent them.
Types of Pool Stains and Their Causes
1. Metal Stains
Metal stains occur when metals like iron, copper, or manganese are present in the pool water. These metals can come from:
- Source Water – Some tap water contains high levels of metals.
- Corroded Equipment – Pool heaters, ladders, and pipes can release metals.
- Algaecides – Certain algaecides contain copper, which may stain surfaces.
How to Identify:
- Iron stains appear brown or rusty.
- Copper stains create blue, green, or black spots.
- Manganese stains turn surfaces purple or black.
2. Organic Stains
Organic stains result from leaves, algae, berries, and other natural debris. These stains develop when debris sits in the water for too long.
How to Identify:
- Green stains come from algae.
- Brown stains form from leaves.
- Red or purple stains may come from berries or fruit.
3. Calcium Scale Stains
Calcium deposits form when pool water has high calcium hardness. These stains look like white or gray chalky patches.
Causes:
- High pH or alkalinity
- Hard water
- Evaporation leaving behind calcium deposits
4. Chemical Imbalance Stains
Incorrect chemical levels can cause staining and discoloration. High chlorine levels, low pH, or unbalanced alkalinity can lead to stains on pool surfaces.
How to Identify:
- Yellow or brown stains from too much chlorine.
- Greenish stains from unbalanced alkalinity.
- Cloudy water from incorrect pH levels.
How to Prevent Pool Stains
- Test Water Regularly – Check metal levels, pH, and chlorine levels.
- Use a Metal Sequestrant – Prevents metals from causing stains.
- Keep the Pool Clean – Remove leaves and debris daily.
- Balance Chemicals – Maintain proper pH (7.2-7.6) and alkalinity (80-120 ppm).
- Brush and Vacuum Weekly – Prevents buildup of organic matter and scale.
Pool stains come from metals, organic debris, calcium, and chemical imbalances. Identifying the type of stain helps determine the best cleaning method. Regular maintenance and water testing prevent stains and keep pools looking their best.
