First sorry about the losses, always sucks. Don't be to quick to blame the vodka, especially if you went as slow as you say you did. I am dosing two tanks...because it works. One a fowlr, and it has worked for a year now no issues. Second a mixed reef with lps, sps, and a carpet for a bit, no issues. Always watch your fish/coral for reaction to whatever you add. But the big thing I watch for with vodka is a possible overdose and a bacterial bloom turning the tank white. If you didn't have that, I would guess the vodka was the culprit.
As mentioned though, you are quarantining your new additions before adding, right?
As mentioned though, you are quarantining your new additions before adding, right?