Our CYA is 80 and Chlorine at 9ppm, which according to the CYA/Chlorine chart is acceptable I believe. I just spoke with the pool maintenance company who did our initial water/chemicals setup (new build last summer), and mentioned to him our CYA/Chlorine levels and he kindof freaked out that the chlorine was "off the charts". He said that is way too high and is corrosive to the copper pipes in our pool heater (which we only use for the spa occasionally, but the way it is plumbed the water flows through it even when not in use). I do have a bag of bio-active that I'm planning to use to reduce the CYA once the chlorine level goes down, but he also suggested I add some type of metal-out chemical to help prevent the corrosion...I hadn't had to add anything like that before so wasn't sure what that would be. I know there are many knowledgable folks in this forum, so I was curious if you agree or disagree with the corrosion concern? I'm still learning as we haven't had the pool a full year yet. Thanks!