Below are a few of the most common materials that lead to surface stains on the pool walls and floor. Their exact effects are always influenced by the water’s overall pH, oxidation-reduction potential, calcium hardness, total alkalinity, and saturation index.
- Iron (Fe)
- Origins: Fill water, degraded pipes or equipment, impurities in salt.
- Evidence: Green water; cloudy yellow, red, or brown water or surface stains.
- Treatment: Sequestering or chelating agent; gentle brushing, or chlorine/acid wash for more severe stains.
- Copper (Cu)
- Origins: Fill water, degraded pipes or equipment, copper algaecides, impurities in salt.
- Evidence: Green, blue-green, yellow, brown, gray, or black color in water or plaster.
- Treatment: Sequestering or chelating agent; gentle brushing, or chlorine/acid wash for more severe stains.
- Manganese (Mn)
- Origins: Fill water, impurities in salt.
- Evidence: Gray, black, lavender, or purple color in water or plaster.
- Treatment:
- Sequestering or chelating agent; gentle brushing, or chlorine/acid wash for more severe stains or gray deposits on plaster.
- Gentle brushing, or acid wash for tougher deposits; balance pH and calcium hardness.
- Fertilizer Stains
- Origins: Fertilizer pellets that get into the water will drop to the floor of the pool. These pellets contain iron and other minerals, which then stain the pool.
- Evidence: Brown spots.
- Treatment: These stains will go away on their own if the pool water is balanced properly.
- Leaf Stains
- Origins: Leaves that have fallen into the pool and are not promptly removed.
- Evidence: Brown stains where leaves have accumulated.
- Treatment: These stains will go away on their own with elevated free chlorine in the water.