I had a batch in the secondary carboy for about a month and the water evaporated from the air lock....not sure how long it's been dry. Any way to determine if this batch is ruined? Thanks so much. Rookie mistake
No, not really. That happens. Vodka will actually evaporate much quicker than water/sanitizer, but eventually your airlocks will go dry due to suck back and evaporation. Refill them, and go about your life.
You are fine. Your beer is fine. Everything is fine.