Need answers, sps struggling

Hi people,



I can and will post pictures when I get home tonight, but the story is that a month ago my chiller died and the tank went up to ~88 deg for a day or two (temp fell to 82 during the night). The chiller got back on track, but I did notice some stress to the tank after that.



Then, about the same time, my calcium reactor stopped working and the alk/ca/mag fell in my system. I noticed this, corrected it, and things were looking like they were on the mend.



Then, about two weeks ago, I went away for a week, during which time I had my kalkwasser drip going 24/7 (this was up from 12 hours a day, I would dose when lights are off). I have no idea how high the pH got when I was away, but the corals were dying when I came home.



Ive done two water changes, and it appears that I've stopped the loss of tissue, but the corals havent started growing back over the dead parts (which is when I will stop worrying).



My alkalinity is now ~9.5, calcium 400 mag 1100 (i know, it's low).



Anyone know what the main cause of the issue is? the dead parts of the skeletal structures are now brown with algae, no new dead spots detected recently, so that's a start i guess.



Suggested course of action?



thanks