Blow-off tube vs./or Airlock?

Discussion in 'Homebrewing' started by miniappletonbrewer2205, Jan 14, 2013.

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  1. miniappletonbrewer2205

    miniappletonbrewer2205 Initiate (0) Jan 14, 2013 Minnesota

    I have a question regarding "blow-off tubing". I recently finished reading the book "Brew Chem 101: The basis of homebrewing chemistry" and learned about the off flavor called astringent which is a direct result of polyphenols (or tannins). The book states that one way to avoid tannins is to separate krausen from the fermenting wort via a blow-off tube.

    I have brewed over 9 homebrews and only once used a blow-off tube to remove the excess CO2 from the fermenting carboy. The one time I did use a blow-off tube it was for the first 4-7 days and then I capped the fermenting carboy with an airlock. Would you recommend always using a blow-off tube during the first few days of fermentation or does the use of a blow-off tube not really necessary. Also, does the blow-off tube actually remove more tannins from the Krausen than an airlock? Please let me know at your earliest convenience. Thank you for your time.
  2. Monsone

    Monsone Initiate (0) Jun 5, 2006 Illinois

    Not sure about the tannins, but judging from the ceiling mopping I was doing last night there are definitely positives to a blow off tube for certain beers :wink:
    JackHorzempa and Rizalini like this.
  3. WickedSluggy

    WickedSluggy Disciple (365) Nov 21, 2008 Texas

    If you are having a problem with atringency in your beers and you have addressed more obvious causes like mash ph and temperiture then perhaps you might consider other causes. Otherwise, I would consider a blowoff tube more a matter of functional necessity and not so much a consideration for effecting the flavor of your beers. If you NEED a blowoff tube, an airlock device is not a substitute. It is actually a debatable issue as to weather or not blowoff improves beer flavor for most of a brewers beers.
  4. mklever42

    mklever42 Initiate (0) Apr 28, 2012 Colorado

    I never use an airlock anymore during the primary fermentation. I will use the airlock base/stopper and attach tubing to the "stem" of the airlock and then run the tubing into a 3gallon carboy with sanitized water in it. I had too many issues with having clogged air lockers. This works great for me and I haven't had any issues for awhile now. Granted, it doesn't change the flavor, just a cleaner fermentation from an equipment standpoint
  5. VikeMan

    VikeMan Poo-Bah (1,561) Jul 12, 2009 Pennsylvania

    Neither an Airlock nor a Blowoff Tube is going to remove any krausen containing tannins unless it actually blows off (overflows). And if it is going to blow off, you need a blowoff tube.
    jzeilinger, WickedSluggy and bbarrows like this.
  6. JackHorzempa

    JackHorzempa Poo-Bah (4,153) Dec 15, 2005 Pennsylvania

    “ …states that one way to avoid tannins is to separate krausen from the fermenting wort.”

    I have always fermented in BIG (7.9 gallon) plastic buckets and I have never experienced the need for a blow off tube. So, all of my homebrews have ‘retained’ the krausen and I have never experienced any astringency in my beers. Based solely on my homebrewing experiences I would suggest that there is no need to “separate krausen” in order to “avoid tannins”.

  7. inchrisin

    inchrisin Initiate (0) Sep 25, 2008 Indiana

    In short, isn't that going to be the same thing as under pitching? This would cause an increase in phenols and diacetyl, among other nasties.
  8. jzeilinger

    jzeilinger Poo-Bah (6,669) Dec 4, 2004 Pennsylvania
    Society Trader

    For me, the use of a blow off tube depends on the volume batch size vs. carboy size vs. OG vs. yeast strain and if it's a recipe I've already brewed I'll also consider my notes from past fermentations in case I need to change something.
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