The Millennium III Series generators combine a 25% sodium chlorite solution with chlorine gas (or 12.5% sodium hypochlorite and 15% hydrochloric acid to form chlorine in situ) under vacuum conditions to generate chlorine dioxide safely and efficiently.  Efficiency and yield is maximized by reaction of chemical reactants in their concentrated form. These reaction conditions favor the immediate formation of chlorine dioxide, thereby minimizing byproduct formation found in other types of generators.  Millennium III generators are capable of consistently producing chlorine dioxide with a yield efficiency of 95 percent based on the overall stoichiometric reaction as follows: 

2NaClO2 + Cl2 → 2ClO2 + 2NaCl