Copper ionization pools and spas that use copper or copper-silver ionization technology to sanitize pool and spa water do not use chlorine to sanitize pool water.  

The Purezone measures FC - Free chlorine - which will not be present in pools and spas that use copper or copper-silver ionization.  The Purezone's FC measurement will not be of any value, however we do provide other water chemistry measurements, pH and Total Alkalinity (TA) in addition to temperature readings.