I have been in this house for almost a year now and likewise, I have been caring for my pool over the same time span. One of the tests that has always perplexed me about my water chemistry was been the calcium hardness test. I had issues with fading endpoints at first but I was able to get that resolved and now I trust the accuracy of the result wholeheartedly.
I have always had high CH reads - anywhere from 425 to 600. I just resulted at 600 ppm. The reason that this confuses me so is because I run BBB. I have an in-ground gunite pool and no SWG. Just straight up BBB. I have never used cal-hypo and I have never had to shock, not ever. This pool is almost 7 years old so there are no plaster curing issues to be concerned with. The only thing that I can think of that would be causing a high CH would be the possibility of the previous owner shocking with cal-hypo routinely. The fact that I have a cartridge filter and therefore, no backwashing or waste settings limits my water elimination to splash out and storm water overflow down the check drain on the tile. To put it this way, my CYA barely moves. I have dropped a total of 5 ppm of CYA over the course of the year. Knowing that calcium and CYA both must be actively removed by draining water, there seems to be no other explanation.
Our municipal water calcium hardness by the way, runs anywhere from 150 to 200 ppm here depending on the time of year.
I don't really have any scaling issues. Should I just leave it alone or should I go ahead and do a partial drain and refill? For what it's worth, my CSI is and has always been within normal limits.