Originally Posted by Bisco_Ben
The stopper is the same stopper as the one that holds the airlock, it is just not drilled. So technically if this could suck into the carboy, so would the airlock. I think I will just give this a try and see how it works out. Te idea of any liquid suckback really bothers me.
Bad idea, the non-drilled stopper WILL get sucked back into the fermenter.
The reason the drilled one with the airlock doesn't is because the airlock allows two-way exchange of air; yes, air CAN go in to the carboy through the airlock (sometimes sucking liquid back in, in the process).
Just use a small amount of Starsan +water solution with an airlock. It'll be fine. I do this all the time.