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How to Determine if Your Beer Needs a Blowoff Tube

Posted by homebrewdad on 6/19/2014 at 02:11:36 PM


I've come up with a simple, foolproof method of determining this whether or not you need to use a blowoff tube when brewing, or if an airlock is sufficient.  Just answer the questions below.

Question one: are you brewing beer?

If the answer is "yes", then you should use a blowoff.

Question two: see question one.

Yeah, okay, I'm being a bit silly... but it's rock solid advice.

I had gotten a little cocky of late; once I made it to really good temperature control (mini fridge/STC-1000 combo), I noticed that my blowoff tubes weren't really doing anything - no krausen was being ejected into the water, etc.  So for the next few brews, I tried using an airlock only; sure enough, this method seemed to work just fine. 

With my last brew (Belgian blonde with WLP530), I was reminded that some yeasts care nothing for my paltry temperature control, that they WILL explode if I don't take measures to prevent it.  Fortunately, I did swap that one to a blowoff before catastrophe struck.  Clearly, I learned my lesson... right?

Of course not.  Sunday, I brewed an English IPA using WLP022 (my first time with that yeast). 

Even with a big, healthy starter (did a one liter starter, stepped it up to three liters, decanted back down to one, saved one vial out for a future brew), I was surprised at how slow things got going.  The following morning, I had an almost nonexistent krausen cap on top of the wort, as well as very slow bubbling.  From there, it grew to a small cap and regular - but not vigorous - bubbling.  I decided that WLP022 must simply be a slow, gentle fermenting yeast.

I tend to check my beer twice a day - once in the morning before I leave for work, and again in the evening after I get home.  Last night, I discovered krausen in my airlock.  Seventy-two hours after pitching, sixty-six hours after I first noticed fermentation... *now* I get krausen in the airlock?  What kind of game are you playing here, 022? 

It did appear that the krausen was retreating, however, so I decied to just let it be.  Yep, you know where this is going.

This morning, as soon as I stepped into the basement, I could smell sweet wort.  While it wasn't the most forceful of airlock explosions, the airlock had indeed been ejected from my carboy, and a thankfully small amount of krausen had spilled out onto the outside of it (and of course splashed the inside of my mini fridge). 

I absolutely, positively know better than this, but since I hadn't really had this problem in so long, I just didn't want to fool with it.  A blowoff inside of the mini fridge is a pain to rig up, I rationalized.  The most vigorous part of fermentation has to already be done, I rationalized.  It's been a long day and I just don't want to bother, I rationalized.

Now I get to clean that carboy and scrub the inside of the mini fridge.  I'm pretty sure that just doing the stupid blowoff would have required less time and effort.

Let this be a lesson to you!  If you are wondering if you should use a blowoff tube instead of an airlock for your next homebrew, simply consult my useful list of questions above.

Tags for this post: blowoff tube, blowoff, airlock, fermentation, beer, homebrew

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I swear by these large plastic buckets: I regularly ferment 5.5 gallons and have never come close to needing a blowoff tube.

posted by Paul on 7/20/2014 at 10:15:01 AM