Copper (Pool Water)
Copper is a dissolved metal found in some pool water that causes blue-green staining when oxidised.
Definition
Copper is a dissolved metal found in some pool water that causes blue-green staining when oxidised.
Typical Values: Staining threshold: approximately 0.5 ppm dissolved copper
In Plain Language
Copper enters pool water from copper-based algaecides, corroding copper plumbing (often in aggressive low-pH water), or copper-core pool equipment. At low concentrations, copper is invisible. When shocked with high-concentration chlorine, dissolved copper oxidises and precipitates as blue-green or teal deposits on pool surfaces and hair. Using a metal sequestrant before shock is the standard prevention.
Why It Matters
Copper staining is a common side effect of using copper algaecide in corrosive water (low pH, low hardness). Understanding the cause prevents recurrence.
Typical Values
Staining threshold: approximately 0.5 ppm dissolved copper
Last reviewed: 2026-06-01