I'm only on my 2nd batch and I've already learned this lesson. I had only 1 and it broke seconds before taking the first SG reading. Just by trying to shake off a couple drops of k-meta solution, POOF! Now I can only "guess" what my alc content is.
I'll be getting an extra carboy as well, since it would have saved me an hour last racking I did. And considering I almost dropped it while cleaning it last night. I would have been screwed.
