This is the principle behind ionization systems. A frequent source of copper discoloration and staining is the heat exchanger in the heater. Corrosion and scaling conditions are dramatically increased by the high temperature found in heaters. As heat exchangers erode, the pool becomes stained and the exchanger tube walls become thin and begin to leak. Finally, staining can occur with the less than proper use of ionization systems and metal based algaecides .
Copper is a known algaestat, while silver ions are a good bactericide.
Copper and silver ionizers inject these metals into the water for contaminant control, however, if the water balance is out of control, or mineral levels are too high, staining can occur. The same is true for the algaecides, although some are chelated, which means they have agents contained in them to prevent minerals from coming out of solution. Preventing Mineral Problems Balanced pool water is such that it has neither a tendency towards corrosion or scaling. At the most basic level, pool water must be balanced to control stains and scale. These agents keep minerals tied up in solution like molecular glue.