Most of the time, I do just fine with the standard-issue airlocks you find at homebrew stores nationwide. But sometimes, an airlock just doesn’t cut it. And that’s when I bust out the heavy artillery. I’m talking about the blow-off tube.

Dave Carpenter Oct 11, 2016 - 3 min read

Most of the time, I do just fine with the standard-issue airlocks you find at homebrew stores nationwide. I prefer the 3-piece airlock for primary fermentation and the S-shaped model for secondary and bulk aging. But sometimes, an airlock just doesn’t cut it. And that’s when I bust out the heavy artillery. I’m talking about the blow-off tube.

A blow-off tube is nothing more than a generous length of wide-diameter tubing. One end plugs into your fermentor in lieu of an airlock, and the other end is submerged in an adjacent container of sanitizer (I use a spare growler jug). This setup effectively relieves pressure within the fermentor and allows Kräusen (foam) to safely escape rather than clog the airlock, thereby saving you from a beer eruption and the embarrassment of having to mop the ceiling.

So, how do you know you need a blow-off tube before you actually need a blow-off tube? Here are a few criteria I consider when deciding to reach for the blow-off tube instead of a regulation airlock.

The goal of all of this, of course, is to prevent a mess. Another way to keep things clean is to leave the lid open and conduct an open fermentation. But that’s a topic for another day...

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