Very high calcium and TA

Good morning to all,

I've been a BBB convert for 3 years. I have followed all of the posts here and solved many problems over the years by your advice, but this one I need some expert advice on.
I have a 20,000 gallon plaster pool. My numbers with a Taylor drop kit are: pH 7.0, CYA 30, FC 2.0, CC 0, TC 2.0, TA 500, CH over 1500.
I am going to lower my TA first (I've done this before with Ben's procedure with great results). I don't understand the high Calcium levels however. We have high iron and calcium in our fill water (over 200) I use a sequestering agent at opening and all year every time I add fill water. ( I had to embark on a lengthy stain removal process last year - that I learned from this forum.) Tap water is the only source available to me right now. So, in short...knowing the problems with my water I am adamant about keeping my pH around 7.3 all year to keep the metals off the plaster. I don't know enough to figure out saturation index and am concerned about heater elements and the pool plaster.
Any thoughts or suggestions would be really appreciated.

I don't know where the Ca is coming from but you need to get your T/A down or you'll get a milky pool. You lower pH--since you have concrete you can go as low as 6.8 or 6.9, then aerate to raise it back up. Dose with acid to lower pH, then aerate to raise it. Get T/A lower--maybe 80 or 90.

Thank you so much, Carl. I was hoping I could find out what TA # to shoot for. Now that I know to stay on the low side, I'm good to go.
Enjoy the rest of your holiday weekend.

....To those of you on this forum that have served our country, our deepest gratitude from me and my family.

Margaret