OK, I replaced about half the water in the pool. Readings, subsequently, were FrCl 0.5, pH 7.1, TA 40, CYA 70.
I added 5 lbs. soda ash - next day readings were FrCl 0, pH 8.0, TA 90.
Yesterday, I added 4 gal. of 6% bleach. Result today: FrCl 6, ph >8, TA 80. Throughout, CH has read zero with...