Making my first batch! Using a Brooklyn Brew Shop kit, and did the active part last night. I've got the jug in a cool/dark place and it it bubbling away, sending CO2 through the tube in the top of the jug into pot of bleachy water. My question: why bother taking out the tube and installing the airlock, like the instructions say to do after a couple of days? Why not just leave the tube in there, going out to the bleachy water? Seems to serve fine, but then there might be something I haven't considered.

3 Answers 3


Short answer: sure, that is fine and jsled is absolutely right.

Long answer: the other thing to consider is just don't bother with blowoff, which I assume is the reason for the bleach water setup, and just use an airlock.

I think being really concerned with blowoff is probably a side-effect of following old Charlie Papazian instructions or people who followed his lead. I know he said blowoff gets rid of a lot of unwanted gunk and fusel alcohols that affect taste of the finished product, but I'm not so sure that's true in a negative (or any?) way and I don't think large breweries tend to worry much about blow-off either. Plus it seems to me there is a slight risk of infection from using/changing blowoff tubes.

You need blowoff if your vessel is too small, but nowadays I personally would use a bigger vessel.

  • Ah OK. The kit that I was given uses a 1-gallon jug, which is almost full. I guess that's why the instructions call for blowoff. But then why would they bother calling for you to take out the tube and fit the airlock after a few days? Oct 4, 2015 at 16:24
  • Other than that some people probably don't want a big gunky container of bleach awkwardly lying around, probably no real reason.
    – Bolwerk
    Oct 4, 2015 at 18:37
  • Oh, well, you might also think of it as a minimum time to leave the blowoff tube set up. :-D But I think it's up to you whether you let fermentation finish out with that sort of airlock.
    – Bolwerk
    Oct 4, 2015 at 19:31

Yes, you can leave the blow-off tube in place if you like. It is just a big airlock, anyways.

  • Cool, thanks for the answer. Why do people bother with airlocks if the blow-off tube accomplishes the same purpose? Oct 4, 2015 at 15:36
  • Some of us don't. :) As BBS point out, an airlock (or just foil over the mouth) is more self-contained and tidier.
    – jsled
    Oct 5, 2015 at 19:01

Using an airlock certainly makes handling the vessel easier as it's all self contained, but hopefully you won't have to handle the vessel much.

I liked using an airlock because it was a more compact and simple setup. However, after having a batch overflow the airlock and make a mess while I was out of town my wife insists that I use a blow-off. I'm happy to do that as there is little functional difference between the two and using the blow-off tube eliminates the chance of making a mess again.

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