This is my 3rd year of BBB, having been previously trapped in the pool store Chlorine Puck Prison.
My 18K Gallon plaster pool was opened ten days ago. No major findings, mostly clear water and the usual (porous cover) debris on the bottom. Cleaned up and shocked (with 6%) nicely. I did 'overshock' at the opening as it is late in the year and green creepy critters were gaining a home on the top foot or so of the walls. I hit the pool with 16 Gallons of Wally World 6% bleach and the water was clear and sparkly within a couple of days. Using the Pool Calculator I added around 4# of baking soda and the same of stabilizer. TA at the time was measured at 50. It crept up over the next days to 60 and stayed there. I figure that is slightly low but do not like to add too much of anything to prevent an 'overcorrection'.
Calcium hardness started at 50, was up to 210 after a week (target was 300) so I thought all was on track. The next day CH dropped suddenly to 140. That's when I must have messed up. The Pool Calculator advised 27 pounds of Calcium Chloride. I didn't want to hit that much at once so I added 13 pounds. CH came back up and is now at 320. FC was also dropping so I added the 3 Qts bleach the calculator called for. Before adding Calcium Chloride the TA was measured at 60, still not getting my attention.
TA suddenly took off. The next day it was measured at 350. I thought I may have gotten a bad reading so did nothing about it until today. Retesting today shows the TA is in outer space at 750! What????
Ph has been steady from the opening until yesterday at 7.2. Today it crept up to 7.4.
For what it's worth, it is very hot and has been for the week or so - mid to high nineties. The filter is running 12 hours per day (8A to 8P).
I am stumped about the extreme TA readings. It appears to have been hijacked by adding CC in support of CH, but that is conjecture.
All ideas are appreciated because I am stumped!