Guys, don't misunderstand me. If you want to use starsan, vodka or anything else besides water, knock yourself out! It's your beer. But you're using it as a safeguard against a fermenter inhaling, which really shouldn't be an issue if the wort is properly chilled and you've used a correct yeast pitch. Both of those techniques are far more appropriate for making good beer than a bit of sanitizer where it's minimally effective.
It's all about the positive pressure coming out of the fermenter. An airlock is a classic Pasteur S that prevents outside contamination into a container. You could leave the airlock dry because Pasteur proved nothing falls up. Plus, the constant flow of gas during fermentation is not going to let anything passively fall into the airlock. During fermentation, water will take on an acidic quality simply from the CO2 and other gasses coming from fermentation. This reaction can turn water cloudy, depending on the mineral profile.
Post fermentation, the liquid in an airlock is simply a barrier between two gasses that want to mix. Alcohol will want to evaporate at room temperature, leaving you with mostly the distilled water they used at bottling after a couple of days.
If your fermenter is inhaling post krausen, then it has too much headspace. It probably needs to be transferred to a container with very little headspace. If you're relying on the same half ounce of sanitizer you used during primary fermentation, then I'm doubtful of it's effectiveness.
