Plus what are you adding to the pool?

Common source of copper is copper-based algaecides. The cheaper ones often supply copper ions rather than complexes and, if too much is used, will result in green pool water.

If the water changes color after chlorine (or any other oxidizer) is added, the swimming pool water probably contains a metal.


Shock the pool to oxidize the metal, which then settles out of solution and looks like rust. The rust can easily be vacuumed out of the pool.

Add a sequestering or chelating agent, which forms complexes with the metal and prevents it from being oxidized by the chlorine.

If the source of the copper or iron cannot be established or if it cannot be avoided, regular addition of a chelating agent or sequestering agent (metal out products) will ensure that any new metal arriving in the pool water will be held in an inactive complex.