The Model Aquatic Health Code (MAHC) Network is a community for MAHC users, subject matter experts, and those hoping to learn about the code itself. Members will receive updates on the code, have access and provide input to newly developed resources, and join bi-monthly webinars featuring the code and users.
On January 30, 2018, NACCHO hosted a MAHC webinar on cyanuric acid:
Cyanuric Acid: It’s Not Just About Crypto
The maximum recommended concentration of cyanuric acid (CYA) to be used in pools has been debated for decades. The debate has continued because it is difficult to determine at what point the reduction in HOCl activity becomes a public health risk. There have been numerous studies that have demonstrated increased inactivation times with chlorine in the presence of CYA, but none that linked these changes in microbial concentration to an increased risk to swimmers. This presentation summarizes the work of the CYA Ad Hoc Committee that addresses this issue. This includes a new look at the literature on the effects of CYA on microbial inactivation using HOCl for chlorine in CT plots. A model is presented for simulation of the steady state concentration of pathogens in pool water under a variety of conditions. This model is applied to estimate the risk of disease transmission to swimmers in the presence of CYA, specifically for E.coli O157, Giardia and Cryptosporidium, and thus provide guidance on its application in swimming pools. As such, this model may be used to inform public health policy for swimming pool management in such codes as the Model Aquatic Health Code.
Richard Falk has been deeply engaged in the areas of pool and spa water chemistry for over 13 years. His deep analysis of the chlorine / cyanuric acid relationship has been helping the Council for the Model Aquatic Health Code develop scientifically sound principles for regulating Free Chlorine and Cyanuric Acid. He is a member of the CYA Ad-Hoc Committee of the CMAHC.