You’re quite right Jerry! Potassium metabisulfite would be fine to use in the airlock. The sulfites do tend to bind and atomize in a fairly short time period so it’s not a great long term, bulk aging option but when you’re in the throws of fermentation I’d think it’s just fine.

-Matt

I’ve used potassium metabisulfite at sanitizing strength in my air locks, not sure why a few drops into the carboy is an issue, as it’s added in the winemaking process as a stabilizer/preservative?

Hello Rancho Fuego! I recommend only using liquids that won’t harm your wine if they end up in the carboy. It can happen during temperature drops or when removing the airlock.

Plain water is what I usually use but adding vodka can be done to help keep spoilage micro-organisms at bay. Another option is to add water and then just enough mineral oil to cover the water. Mineral oil is food grade, doesn’t evaporate, and doesn’t spoil. Because it is oil, if it does end up in your wine it will float on top and is easily racked off of.

Most sanitizers aren’t something you want in your wine thus I recommend avoiding those.