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CYA and The Relationship To Chlorine In Your Pool

The topic of Cyanuric Acid (CYA) is a common one and one that has been discussed in the news a lot more lately. There are also several swimming pool industry magazines that have recently published articles about it and we have had several calls from potential Service Providers in Oregon and San Antonio that are looking to use Reverse Osmosis (RO) filtration to lower it. So we felt it was important to discuss CYA again and why it can be challenging to manage water chemistry when the levels get high.

Chlorine is one of the most important chemicals used to keep your pool water clear and free of algae if used appropriately. Whereas, the most common chemical used to prevent chlorine loss in swimming pools in CYA. There is a direct correlation between the two and we are going to discuss how to lower CYA levels when they get to high. During the long, hot summer months the sun’s ultraviolet rays destroy free chlorine but having the proper amount of CYA in the swimming pool can prevent this. This can be achieved by adding CYA to a swimming pool in the beginning but if you use chlorine tabs, this level will continue to rise.

With that said, if CYA is used properly it can reduce the cost of maintaining a swimming pool because it prevents chlorine loss and reduces the amount of chlorine needed to properly sanitize a swimming pool. But, over time CYA levels will increase in your swimming pool because many swimming pool owners and pool professionals will use chlorine tabs and those tabs contain Cyanuric Acid!

So, what are the normal levels of CYA in a swimming pool? Typically, the ideal amount of CYA is between 30 – 50 parts per million (ppm) but depending on how much direct sunlight the swimming pool gets, that number might need to be a little higher or if you use a salt chlorinator you should refer to the manual for what it suggests. Whereas, when the CYA levels rise above 100 ppm, that can cause a fair amount of other problems too. The biggest issue when CYA levels rise above 100 ppm is the effectiveness of chlorine because the higher levels tend to bind up the chlorine making it harder to kill algae and other bacteria. When this happens, most pool professionals will recommend a water change in your swimming pool. This can be done by a typical drain-and-refill which wastes on average 20,000-gallons of water and is a method that we don’t agree with or you can recycle the water with RO filtration which we do recommend.

It isn’t uncommon for us to pull up to swimming pools with CYA levels as high as 100, 200, or even 300 ppm or higher! When this happens it can be much more challenging to keep free chlorine working optimally in your swimming pool because the factor to establish the level of free chlorine needed to combat algae is the level of CYA x .075. So, if you had 300 ppm CYA it would take approximately 22.5 ppm (free chlorine) to keep your pool algae free and that can be challenging especially when the water is warm.

At Pure Water Industries, we are a fan of using liquid chlorine. This doesn’t add Cyanuric Acid to the swimming pool and if you can keep the CYA levels within the normal range of 30 – 50 ppm. the chlorine will work more effectively. If you should have any questions about CYA and the relationship with chlorine please don’t hesitate to contact us today!