I have a gunite pool around 45,000 gallons. My CH was sitting around 225-240 for a week or so. I added around 40 lbs of calcium chloride. Chlorine was at a 6 (CYA 50). This was tested & added when the sun was setting. The next morning chlorine was completely gone. This has also happened once before but I figured maybe it was a fluke or something but since it happened again & I have more calcium chloride to add, I figured I’d try to see if there was a way I could keep this from happening. This was about a week ago & fc has been great since.