CYA values

[Nanifen]

Hi. I’m back. . Things are going well and my alkalinity is slowly dropping.
New question. I did pool school and I get free chlorine, total chlorine and cc. My question involves CYA. I know it’s like sunscreen for chlorine but help me understand why too much is bad? What does it cause?

 

[mguzzy]

A certain amount of the chlorine is bound by the CYA chemically. As the CYA gets higher, a higher amount of CL is needed to perform the same level of sanitation. By this famous chart we all like to quote: FC/CYA Levels
If the CYA gets too high then the bulk of the chlorine it is bound up by the CYA and you reach a point of diminishing return.. there is not enough CL to properly sanitize it. That is the layman's explanation.. the Hardcore Chemistry explanation is in the Deep End forums.

 

[Nanifen]

A certain amount of the chlorine is bound by the CYA chemically. As the CYA gets higher, a higher amount of CL is needed to perform the same level of sanitation. By this famous chart we all like to quote: FC/CYA Levels
If the CYA gets too high then the bulk of the chlorine it is bound up by the CYA and you reach a point of diminishing return.. there is not enough CL to properly sanitize it. That is the layman's explanation.. the Hardcore Chemistry explanation is in the Deep End forums.

Thank you. I like layman’s terms just fine.