Do I start the countdown right after I put the chlorine in?Never mind. I just re-read your last post. Please do the following:
1. Use a SLAM/Shock FC of 10 for now. Temporarily remove the sock of CYA by placing in a bowl or bucket. Or at least pause on squeezing it.
2. After increasing the FC to 10, retest FC at 10-minute intervals.
3. If FC crashes below 5 ppm, add FC to bring back up to 10 and continue retesting FC @ 10-minute intervals.
4. If FC holds between 5 - 10, then add FC to bring back up to the new SLAM level of "12".
5. Now you can put the CYA back in the water and/or start squeezing it again. You want to bring the CYA up to 30 ppm.
That 10-min drill is very important until you see the FC holding.