We starting using the chlorine tablets basically just the first day we opened the pool and then I came on here and learned that's a terrible thing to do , so we shut off the chlorinator and have been using strictly liquid chlorine since then, meaning we have only been using liquid chlorine the past 3 weeks, no tablets.
Our CYA was at 40 at that time and had been pretty steady there. (At least I assume it has been steady. I only tested it a few times thereafter and then haven't tested it in a few weeks because there was no reason to (i.e., no water replacement, etc, except for lots of rain). We were going by the chlorine/CYA chart using our CYA of 40 to determine our FC target levels.
Just tested today on a whim (no real reason to) and CYA seems to be at 50.
What would cause this increase? Is this just the residual effect of that one day (don't even think it was a total day) of using the tablets, taking weeks to affect our CYA level?