CYA still high after water change

[mbar]

I have heard coflicting points on this - first I heard that calcium is a metal and if there is too much in the water, it can stain the pool. Then I heard if there isn't enough calcium in the water, it will draw out metals from the fiberglass. They both sound strange to me. The first year I had stains, before I found this site, my pool had a calcium of 500, I had to drain 1/3 and refill 2 times to get it down. Then I have tried running my pool with no calcium, and I did have more stain than when I kept it at 150 the year before, but I was also playing around with my ph that year. To be on the safe side, I run the pool with calcium of 100 to 150. I think the most important thing in a fiberglass pool is to put sequesterant in the water. Just on Tuesday I had flood water flow into my pool and turn it green. I shocked it up to 30 (I went a little nuts with bleach), and put more sequesterant in it - I didn't get any stains. Also my ph tested at over 8 - but I remembered reading on this forum that high chlorine levels could make the ph test false. I thought it was strange with all the rain for the ph to go up, thank goodness for this site, I didn't add any acid. When I tested that night my ph was below 7, and my alk was 60. I added baking soda and borax, and my numbers were good today, and watter is crystal clear. So I think with the sequesterant, and low ph with the high chlorine kept my pool stain free. My opinion is to keep the calcium at bout 125 in a fiberglass pool.

[waterbear]

I keep my calcium about 200 or sligtly above but not for the fiberglass pool. I have a lot of grouted tilework on the outside of the spillover spa that gets constant water exposure and my spillover is made of marble so the calcium is for that.