Ok I have been haveing this problem going on 2 years now.
Open the pool up and cannot get the fc to read.
vinly 24000 inground southern Mississippi
cya doen't change 0-20
salt acording to aqualogic 3000 ppm
I can shock and shock and shock with Cal Hypo and never get the fc to rise. I have just started the drain and refill process thinkin past years of using 3"tab's wacked out the cya.
Have taken samples to the local store and we can adjust all the chem's in range fine but CYA and FC does not budge. Water clear with very little cloudyness. I mean I can see the suction in the bottom of the deep end fine.
I even bought a new salt cell this year thinkin the 3 year old one was dead.
Help With some suggestions