- The DG7-OZ is a panel-mount, ready-to-use dissolved Ozone (O3) sensor. It provides several measurement ranges to accommodate various applications: 0 ~ 2.00 ppm for disinfection and 0 ~ 10.00 ppm for oxidation and bleaching. Ozone is a colorless to pale blue gas, when in low concentrations; it gives off an irritating acidic odor. Ozone is a strong oxidizer, stronger than chlorine and chlorine dioxide. It reacts quickly, disintegrates into oxygen gas, and increases the amount of oxygen in water when applied to water treatment.