Cyanuric acid also known as Pool Stabilizer, is marketed as a chlorine stabilizer for swimming pools
Cyanuric acid forms a weak bond with free chlorine in the pool
water, protecting it from the sun’s ultraviolet rays to reduce chlorine loss. Properly managed,
cyanuric acid has been shown to reduce the amount of chlorine needed to maintain the minimum
chlorine residual in an outdoor pool. In a small pool with a moderate bather load, cyanuric acid
can significantly reduce the cost for chemical disinfection.
Cyanuric Acid Also have its downside by forming temporary bonds with the free chlorine, cyanuric acid will reduce the overall effectiveness of chlorine. The amount of time it takes to kill bacteria lengthens as the concentration of cyanuric acid increases. For this reason, the Lincoln Lancaster County Health Department recommends that all outdoor pools using cyanuric acid as a stabilizer maintain a minimum free chlorine residual of at least 2 parts per million (ppm).
- I have an indoor pool. Should I use cyanuric acid? – No. Remember that cyanuric acid is intended to reduce the loss of free chlorine caused by the sun’s ultraviolet rays. Indoor pools are not exposed to direct sunlight and therefore, there is no benefit in adding cyanuric acid to the pool water or using products containing cyanuric acid such as trichlor or dichlor.
- How much cyanuric acid should be used in a swimming pool? – Chemical suppliers recommend that the optimal range for cyanuric acid is 30-50 ppm, although a study published by the University at California at Davis , indicates that there is still significant savings in chemical costs in levels as low as 2 or 3 ppm. Other authorities recommend about 20 ppm for a good costto-benefit ratio . At levels above 50 ppm, pools reach the point of diminishing returns where the 2 reduction in chlorine effectiveness and cost of buying cyanuric acid outweighs the benefits. Dichlor by weight contains 57% cyanuric acid. Trichlor contains 54% cyanuric acid.
- How much is too much cyanuric acid? – The Nebraska Swimming Pool Act has set the maximum level at 100 ppm. A 2007 study by the Centers for Disease Control and Prevention 3 (CDC) revealed that cyanuric acid significantly diminishes chlorine’s ability to inactivate the chlorine-resistant protozoan, cryptosporidium. Based on the findings of the CDC study, the Health Departments recommends that cyanuric acid levels not exceed 30 ppm.
- What are the effects of higher levels of cyanuric acid? – As the level of cyanuric acid rises, free chlorine’s ability to act as a disinfectant is weakened. At above 50 ppm of cyanuric acid, the time it takes to kill bacteria in the water is longer compared to swimming pool water without cyanuric acid. Also, as the level of cyanuric acid builds up, the chlorine will become increasingly less effective in keeping the water clean and problems such as increased cloudiness and exceeding combined chlorine limits can occur.
Here are some recomendations by the Health Department:
- Cyanuric acid and stabilized chlorine (dichlor or trichlor) should be used in outdoor swimming pools only. It should never be used in indoor swimming pools, spas or hot tubs.
- Both dichlor and trichlor release cyanuric acid to the pool water. It is not necessary to put additional cyanuric acid into a pool that uses dichlor or trichlor.
- Pools that use cyanuric acid should maintain a free chlorine residual of 2 ppm.
- Cyanuric acid should be tested at least once a week to keep concentrations below 30 ppm.
- Cyanuric acid levels should never exceed 100 ppm.
- Partially drain pool and add water to reduce cyanuric acid concentration
Family Pool Cleaning 