A little background...
We purchased a home in November with our fist ever pool. It had not been closed (guess I don't really need to here in SC) and was crystal clear. Not knowing any better I dutifully took water samples to a pool store (one we purchased a hot tub from, so they like me ). All winter the numbers the pool store came up with were "perfect" according to them (other than CYA which according to them was 98). I suspect that the previous owner just dumped all his chemicals into the pool as he was leaving, but I can't prove it.
Just for giggles I went to a second pool store and they also said I was OK, but they came up with 151 for CYA. According to them I was getting close to "chlorine lock".
I decided to take matters into my own hand and began searching and found Ben Powell at his web site The PoolForum. After a lot of reading I decided the BBB Method was for me. I purchased a Taylor K2006 kit and began testing. A little more poking around brought me here.....
My first numbers from my testing at the beginning of April:
CYA 200+ (even diluting the sample it was off the scale)
The only thing I have been using is bleach and muratic acid for over a month. I have been quick to back wash and refill the pool with tap water. Today I drained it to the the skimmers and refilled. Now I can see a CYA number (still by diluting).
This afternoons numbers
I still have to work on getting the CYA below 100, but everything is moving in the right direction. My nly issue will be keeping the FC up when we go away a couple of times this summer. Right now it is working out that I only need to add one gallon of bleach about every 2.5 - 3 days, but we do have a couple of week long trips scheduled.