I cannot keep FC in my pool this year. I had a bit of a problem last year, but it is much worse this year. We are adding a gallon of bleach nearly every day to keep up. Let it lapse a few days, and the FC drops to 0 and the pool immediately turns cloudy, can't even see the bottom.
~28K plaster pool. DE filter, solar heat, IC 40 salt cell. Pump runs about 12 hrs / day during the day.
TF100 test kit results:
Water temp 85
Salt level 3200
FC - goes to 0 quickly
I have been trying to get CYA up, but no matter how much stabilizer I add, it never seems to change. Had the pool store test, same results. Bought new CYA reagent, same results. I've probably put in 10 lbs of CYA this year, no change. Filters cleaned, DE replaced, salt cell acid washed, etc.
Pool store, of course, said we have high phosphates. We ignored that.
We only use liquid acid when pH needs help, and bottled bleach. Maybe a bit of polyquat at closing time, along with RV antifreeze in the lines. Nothing else hits the pool. Well, except for Katy the wonder dog.