Air Lock

we've always used plain water in clean & sanitized airlocks w/o any probs...

I put a little sulfite in mine but it isn't necessary.

The only qualification I would add would be when cold stabilizing so it does not freeze. I use cheap vodka or some really bad hard liquor; I have a horrible tequila I use for airlocks going into cold stabilizing at this point.

Joe

I usually use sulfite solution but I have used water with no problems.

Ray

As an idiot, I always had a slight issue with using sanitising solutions (non-sulfite) in airlocks. On a few occasions I have suffered backdraft (due to removal of a 'rubber boot' based airlock and in placing large soft rubber bungs into the carboy). I.E. A few times there has been fluid sucked back through the airlock which has ended up in the wine. I haven't had the airlocks too full as far as I can make out, but I am pretty sure a little fluid has made its way in there. If it hadn't been a mild sulfite solution I had in there, but a more general solution I would have veritably lost my composure at potential reactions (though the wine just shrugged and got on with it).

Jim