My pool is about two years old now and we really we have been enjoying it. Understanding the BBB method has made taking care of the pool so easy, and the water looks great. From the research I read on the forums most people tend not to worry to much about low CA, as it tends to creep up on its own over time as water is added, or powdered calcium Hypochlorite is added. I added hardness increaser last year to try and get close to 200 ppm as I was around 150ppm. But really didn't monitor CA much after that as I figured it would hold or creep up on its own. Every time I did test for CA, it was never above 200, but CSI was always between -0.4 & 0. While swimming the last couple of weeks I've noticed several Pits in the Pebble Finish (Wet Edge), some very small where a pebble was just removed, but others about the size of a nickel. One of the deepest ones (feeling with my finger) is maybe 1/16" deep. They are only found on the floor, thus far, and in many different places.
I tested the water today after noticing one of the larger pits and the CSI came out to -0.3, which isn't quite balanced, but not at -0.6 either.
My pH stays between 7.4 - 7.8, usually on the higher side.
TA runs 70 - 80
Borates just recently added to 50 ppm
I'm going to start adding Cal-Hypo for a short period to bring CA up.
Do you think this could be the cause of the pitting??
How thick does the plaster tend to be? Should I be worried about these locations? Have I damaged my Finish
Anything else I should do or monitor?
I was worried in the first year as my Polaris 9300 would have about a tablespoon of pebble each cleaning. Thus, I thought I got a bad plaster job, but it decreased significantly after about 6 months, with almost no pebbles in the filter when cleaning this past year.