For weeks now, my CYA has measured less than 60 (using the R-0013 CYA Reagent bottle to test this). Since I have a salt pool, I'd like it up around 80 I think. I keep adding 3" chlorine tablets because somebody from this site told me that each tablet should raise my level about 4.3 ppm in my 7600 gallon above ground pool. I feel like over the last several weeks I've added 4 or 5 of those tablets, and I'm not seeing any CYA change.
However, could one of these three things be the problem?:
1) We've had a lot of rain, and several times I've backwashed to get the water level back down to the top of the skimmer opening, as the skimmer won't operate correctly when the water is past the skimmer hole.
2) My R-0013 bottle is a year old. Does those things go bad after a year?
3) My chlorine tablets are a little more than a year old. Do those lose their CYA after sitting in the bucket that long?
Well, I did just use up the last of of my R-0013, and I'm about to order another one, so if (2) above is the problem, I'll hopefully get a good reading soon. If you experts here think that (2) is something to worry about, then I better put a halt to adding those chlorine tablets, for fear of overdosing my pool with CYA.