The Clearwater Pool System is the closest thing possible to a chemical free swimming pool as you can get.
The copper ions help control algae.
The MineralPURE ionization system consists of a state-of the-art micro-processor control box and a scientifically designed set of electrodes composed of copper or copper/silver. These are set slightly apart from one another. Water is passed through a specially designed flow cell chamber that houses the electrodes. The control box works by generating a precise, low-voltage, DC current (at milliamp levels) to the electrodes.
Basically, the current causes some of the outermost atoms of the electrodes to lose an electron, thus becoming positive ions. While the water is running through the chamber, many of these ions are swept away before they can reach the other side of the electrodes. As a result, copper or copper & silver ions are dispersed into the body of water that is being purified.
The greatest benefit of copper or copper/silver ionization is that the ions remain in the water providing a residual protection. They provide long-term, nontoxic purification and prevent against recontamination. Unlike most types of sanitizers, the copper and silver ions remain in the water until they flocculate, or form masses with the algae and bacteria and then become large enough to be removed by the filtering equipment. When the “used” copper and silver ions are removed, the microprocessor control box is always producing new ions to continuously sanitize the water.