plastic tubing instead of airlock?

[peachwein]

I've been seeing pictures of carboys that have a long fat plastic tubing going from the carboy to a bucket of water. What is the advantage of this? Why isn't a standard airlock used in these cases?

 

[herbler]

It's used in case you have a massive fermentation that could clog and shoot beer, trub and said airlock all over the ceiling! After attenuation is reached, you can replace with airlock. Search for photos of the carnage - hilarious!

 

[TVarmy]

That's a blowoff tube, used when there's too much krauzen or CO2 for the airlock to handle. An airlock, of course, is smaller and more convenient, so the blowoff is only used when needed.