Just did my weekly full chem test, and my CYA went down. I thought it was very hard to get CYA out of the water, without removing water...is that not the case?
CYA: between 40 and 50.
pH crept up because I had to add salt yesterday, and left the spa spillway on to help agitate the water. Probably not needed, but that's OK.
I'll treat all accordingly per pool math, just curious if the CYA decrease is normal. EDIT Does it go down with evaporation, or does it act like salt and never leave unless water is removed?