36 hours ago I brewed a BIG red ale and pitched some kick-ass WLP001. The picture on the left is what I had late last night (24 hr in). Made me a little nervous. And this morning the krausen had nearly reached the stopper.
In the pre-work morning rush I rigged up this blow-off tube with a 1/4" tubing, the universal stopper, my 6 gal brew kettle (the most readily available container), a HUGE binder clip (for weight), 2 qt. of water, and a little sanitizer.
With a little coercion, the tube fit tightly into the stopper and CO2 starting bubbling in the kettle.

This got me thinking, what's the best way to do this? What size tubing? The elevation of the container vs. the elevation of the vessel? How much water? Sanitize it all?

ps- don't mind my cluttered closet

krausen alt text

  • Great question. I've wondered it myself after having a 1.095 beer blow the airlock...
    – JackSmith
    Commented Mar 9, 2010 at 16:59
  • 2
    You definately want the blow off collection vessle to be below your fermentor. As the fermentor cools post fermentation activity it is possible to create enough of a vacuum that the blow off liquid will get sucked back into the fermentor.
    – brewchez
    Commented Mar 9, 2010 at 18:38

1 Answer 1


I've always used a tube that was biggest enough to fit snug into the neck of the carboy with no stopper.

I use a standard mix of sanitizer and a pot/bucket with enough in it sitting at the right height so that the open end of the tube is submerged. That's pretty much all you need to do.

What you have in the pics is just fine. You're goal is to have some place for the blowoff to go and to prevent anything from getting into the beer. Which, however, is highly unlikely anyway with the amount of CO2 blowing out of the tube but better to be safe than sorry.

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