In the four years that we have had our pool, chlorine and acid is about all we ever need to add. Our CYA and TA levels have always been stable. Now, without any rain, only adding about 2" of water to the pool, and running the heat pump the last couple of weeks, our CYA has dropped from 40 to not even registering (I checked it several times with a brand new test kit), and our TA went from 120 to 80. I used PoolMath and added what needed to be added, but any suggestions as to what could have possibly happened?
CH540 (it's always been high and we've never had any signs of scale)
CYA Not even slightly cloudy in the tube (I entered 0 for CYA in PoolMath)
Thanks for your help!