This is the order of priority:

1. Maintain an adequate chlorine level
2. Maintain a pH level of 7.8 or below, but not much below.
3. Establish an adequate stabilizer level.
4. THEN look at your calcium and alkalinity levels and see if adjustments are necessary.

Attention mods and support team members: there is a LSI calculator, here:
http://www.lenntech.com/calculators/.../langelier.htm
If you run her numbers (TA:100; CH:200 with a TDS of 2000 and a water temp of 85F (note the F/C selector!) you'll see that she's LDI neutral at 7.4 and slightly OVERsaturated at 7.8. So currently there is ZERO need to add calcium OR alkalinity. In general, a high TA is NOT a benefit, and with her pH, any corrosion that occurred, even with much lower TA and CH would be VERY slow.