My mead fermented in a bucket for a month using Ken Schramm's staggered yeast nutrient technique. I've racked it to a glass carboy for aging. Can I plug the top of the carboy with a solid stopper? Or do I need to use an airlock?
an airlock is the safe bet, were your hydrometer readings steady at the end so you now the ferment was done? it's doubtful you'll get a full blown eruption but if even a tiny bit of fermentation is going on the solid stopper becomes a missile, I wouldn't wedge it in real tight, just enough to seal.