I opened my pool a few weeks ago (It was a breeze by the way, thanks to TFP). Upon opening, my CYA was right around 35. And, I tested it a week later, just to be sure. Still at 35.
I did my monthly CYA test last night, and the water in the tube was clear as can be when the water reached the very top. My pool is around 28,500 gallons. I have vacuumed to waste one time, which hardly dropped the water at all (with one garden hose running into the pool). And we drained about an inch of water off the top due to heavy rain a week ago. Could that be enough to have made the CYA drop THAT much? I would THINK not, but who knows???? My CYA test regent bottle will be a year old in July, it has been stored inside the house. Don't know if that would have anything to do with it? I tested again this morning for the heck of it, and got the same results as last night.
I do have some pucks left over from before I stated TFP methods, I kept them around in case I ever needed to boost CYA this year. If this new CYA level is correct, how many would I need to raise my CYA back up to the 35-40 range? The following link is to the pucks that I have.
http://www.intheswim.com/Pool-Chemicals ... mmer-Tabs/
Thanks in advance!