My cyanuric acid (CYA or stabilizer) is higher than 50ppm. What should I do?

Cyanuric acid (CYA) is used to ‘stabilize’ chlorine. In the correct concentration of 30ppm – 50ppm, CYA will keep the chlorine active in the water longer and slows the process of chlorine ‘gassing off’ from aeration or the sun’s ultraviolet rays. However, if CYA goes above 50ppm, it can lead to problems including ‘chlorine lock’. This is a state in which the chlorine is no longer effective because it is ‘trapped’ by the CYA.

CYA is commonly found in chlorine tablets. These tablets will sometimes be labelled as ‘dichlor’ or ‘triclor’ and may say ‘Stabilized Chlorine’ on the packaging.

Some pool builders and service companies recommend adding CYA to saltwater pools to keep the chlorine in check and help preserve the chlorine generating cell.

If you have a CYA level higher than 50ppm, the only way to reduce it quickly is to dilute the water. This means you will have to drain a portion of the pool and refill it.

If you are getting close to the limit, you can switch to ‘unstabilized’ chlorine tablets (chlorine tablets which do not include CYA). You can also use liquid chlorine or bleach. Over time, the CYA will gradually dilute as you add fresh water.