I have an Artic Spa (360 gallons). It has ozone and SWG. I only use the Artic Spa chemicals, basically Boost (cholrine), Refresh (nonchlorine shock), and Ph up and Ph down).

When I test the water the CYA is at 80? I never added CYA nor used any products containing CYA. It must be coming from my pool as people (mostly kids) go from pool to spa to pool. My pool CYA is at 50.

I understand CYA as it relates to pools, but how about hot tubs? How high can I let it go before I need to drain it?

Thanks!

Is the active ingredient in your chlorine dichlor???

If so, there's your CYA.

I found a picture of an Arctic Pure Boost bottle, which shows the main ingredient as sodium dichloro-s-triazinetrione, aka "dichlor" which adds almost as much CYA as it adds chlorine. On the other hand, I found another webpage guide where Boost was identified as lithium hypochlorite, no CYA there. Check the ingredients on the bottle.

I recommend Nitro's Approach to Water Maintenance which works extremely well.
--paulr