Chelating Agent

Chelating agents can also be called stain inhibitors and sequestering agents.  Chelating agents help to inhibit stains from occurring in swimming pools that by combing with the dissolved metals in the pool water, preventing the metals from becoming free from the solution and thus staining the pool floor, walls or water.

Stains to the floor, walls and discoloration of swimming pool water can often be the result of dissolved metals such as copper, iron, or manganese. The stains can be gray, green, black, or brown. A chelating (or sequestering agent/stain inhibitor) can help prevent stains from occurring by combing with the dissolved metals, preventing those dissolved metals from combining and reacting with other metals or chemicals in the swimming pool, which is when stains happen.  Often times, pool owners and service professionals notice that pool water is green, but quite clear.  This is one sign of iron or copper being dissolved and present in the pool water that might be diagnosed improperly and then treated as an algae occurrence.  A quick test from a water sample brought to a local pool supply store may be able to identify it as definitely staining from metals.  If this is the case, a chelating agent can be added, the filter run and lower sanitization levels for about 72 hours to prevent further staining.  In addition to adding the chelating agent, the pool water should be tested for balance, otherwise the chelating agent will be added in vain, while pool equipment continues to corrode and deteriorate.  If staining has already taken place to the floors and/or walls of the swimming pool, a commercial stain-remover and a good brushing may remove them. Otherwise, if the stains are left untreated for too long, the only way to remove them would be by draining and acid washing the pool.  Before it gets to that point, it is recommended to test the water and use a chelating agent, avoiding costly, long term damage.