Since my pool was built in April, my CYA consistently tested at about 70 for about the first 2 months. I've been using BBB since day one so that it won't go any higher. I went on vacation for a couple weeks last month, and used Trichlor pucks while I was gone to make it easier on my neighbor. I wanted to see how much the Trichlor pucks raised my CYA , so I waited three weeks before testing CYA again, and now I have a CYA reading of 45. (I did it twice to make sure). I'm using a TFP test kit.
I don't backwash (cartridge filter), I don't have a leak (bucket test) so what could be making my CYA drop?
I have a theory that in very sunny/hot/dry conditions (such as southern AZ where I live) CYA naturally "disappears". Is there anybody else who has experienced this?
Can the Chem Geeks back this up or give any insight into what is happening? I currently use bleach for my chlorine source, but if my CYA is going to disappear naturally, I'll just use trichlor pucks as they are much more convenient.
13000 gallon in-ground gunite