Thank you. Is calcium harness the same as total hardness? I have a Pentair test kit for total hardness and the Taylor kit was for calcium hardness??

I've had to drain 75% of my pool water due to high cya reading of 100ppm. I could not get a chlorine reading of even 1ppm so thought I needed to add more tablets and didn't realize I was also adding more stabilizer. I also noticed a few spots of black algae appearing which was another red flag that my chlorine was no longer effective. I was shocking w/3 lbs calcium hypochlorite once a week during this time as well. I think this overchlorinating with the trichlor and the shocking over a long period of time are to blame, but at this point I feel clueless? I had no idea about stabilizer and just followed the advice of the pool stores? I use a sand filter and the pool is 30,000 gallons.
Readings I did get since the drain and refill:

ph 7.8
alkalinity 80

I still cannot get any chlorine reading, still showing zero. I had assumed the cause was either the No Mor Problems masking the chlorine test or the high stabilizer level. Ran out of solution to retest for the acid level after the pool refill and 12 hr pump circulation of that water. I won't have more test reagents until Wed for that and today is Sun. I had to order more online since the pool store I usually go to here is all out. Because I don't know what if there has been a successful reduction in acid level or even what the actual reading is, I am at a loss for how many gallons of bleach to add? I plan on following the BBB method henceforth.