With my new TF-100 test kit, I had been measuring CYA at 40-50ppm. I actually feel pretty confident in my ability to perform this test. I'll perform it 2-3 times in a row and always get the same exact result. I'm also getting consistent results from day to day and week to week. So, I wanted to get my CYA up to the 70-80 range that is recommended by TFP and by my SWG manufacturer. I recently added 4 lbs of CYA, and the pool calc says this will add 20ppm for my 25k-gal pool. However, I'm still reading about 50ppm. I added the first 2 lbs by dissolving in a bucket and painstakingly pouring the dissolved slurry into the water, then refilling and letting the remaining portion dissolve some more. 1/2 day. I then added the last 2 lbs by putting it in a sock in the skimmer. That took every bit of a week to fully dissolve (8 days). It's been about 5 days since the contents of the sock fully dissolved.
Why is my CYA not measuring higher?
I know that most people at TFP don't think very highly of pool store employees, but I should add that my PS guy said that you can sometimes add and add and add, and you might find it impossible to get CYA up near 80ppm or over. I'd never heard that before. Is there anything to that?