What Is Cyanuric Acid?
Cyanuric acid is a chlorine stabilizer, and the CDC says it is also found in chlorine products commonly known as dichlor or trichlor. When it is used, the CDC recommends a pH of 7.0 to 7.8 and a chlorine concentration of at least 2 parts per million in pools, and recommends not using cyanuric acid or chlorine products containing it in hot tubs.
The trade-off is slower disinfection. The CDC says its chlorine disinfection times for germs apply only to pools and hot tubs that do not use cyanuric acid, and that disinfection times are longer in its presence. The annex to the 2024 Model Aquatic Health Code says substantial laboratory data shows inactivation times for microbial contaminants are increased in the presence of cyanuric acid, though a limited number of studies have examined the impacts under aquatic venue conditions.
Codes set ceilings. The CDC's 2024 Model Aquatic Health Code, a voluntary model for states, says the cyanuric acid concentration at all aquatic venues shall remain at or below 90 parts per million, and that if the level is 300 ppm or higher the venue shall remain closed until immediate remediation has occurred. Indiana's rule for public and semi-public pools says that if chlorinated isocyanurate or cyanuric acid stabilizers are used, the concentration shall not exceed 60 ppm.
Sources checked September 15, 2026. Every point below links the page it came from.
The sources behind this answer
- Government sourceThe CDC calls cyanuric acid a chlorine stabilizer, also found in products known as dichlor or trichlor, and recommends pH 7.0 to 7.8 with at least 2 ppm chlorine in pools when it is used. CDC ↗
- Government sourceThe CDC recommends not using cyanuric acid or chlorine products with cyanuric acid in hot tubs. CDC ↗
- Government sourceThe CDC says its chlorine disinfection times apply only to pools and hot tubs that do not use cyanuric acid, and that disinfection times are longer in the presence of cyanuric acid. CDC ↗
- StudyThe annex to the 2024 Model Aquatic Health Code says substantial laboratory data shows inactivation times for microbial contaminants are increased in the presence of cyanuric acid. CDC, Model Aquatic Health Code Annex ↗
- Medical referenceThe 2024 Model Aquatic Health Code says cyanuric acid at all aquatic venues shall remain at or below 90 ppm, and that a venue shall remain closed until remediation if the level is 300 ppm or higher. CDC, Model Aquatic Health Code ↗
- Regulatory filingIndiana's rule for public and semi-public swimming pools says that if chlorinated isocyanurate or cyanuric acid stabilizers are used in a pool, the concentration shall not exceed 60 ppm. Indiana State Department of Health, 410 IAC 6-2.1 ↗
Sources checked September 15, 2026. A brand statement is the company’s own claim, which we report but have not verified. Our grades are model-based estimates, not lab tests.