I didn't see his topic. Sorry if it's a repeat.
I finally got rid of the algae with bleach and shock on the second try.
Now the pH is 8.2 and the T/A is 170. FC-18, TC-17, CH-240, CYA-80
The last time when the algae was attacked I ended up close to these numbers. I added Muratic acid and the pH dropped 0.2. I added a gallon and a half. Surely that was enough? The TA didn't budge.