The Effect of pH on Monochloramine and Free Chlorine Efficacy This chart illustrates a theoretical effect of pH on the efficacy of monochloramines and chlorine and should not be relied upon for scientific purposes or applications. Contact Legionella Control Systems for more information and the potential application of this information with your water systems, or if you are aware of studies that more accurately quantify this effect. Relative Efficacy of Monochloramine vs. Free Chlorine vs. Legionella Suggested Systems Monochlorine System for Legionella Control Partner with experts who understand ORP and have the engineering and technical expertise to ensure the best solution for your facility. Schedule your risk assessment and testing today—contact us at [email protected] or call 888-416-8626. Request Proposal Contact Us