Author Topic: Airlock vs. Blowoff tube  (Read 1301 times)

Offline ngordon34

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Airlock vs. Blowoff tube
« on: November 24, 2014, 03:16:47 AM »
  I brewed my first AG milk stout 2 days ago and pitched with Wyeast 1056. I made a 1.5L yeast starter prior to pitching and also use a small chest freezer that I have converted into my fermentation control chamber. So iv noticed people asking questions related to adding a blow off tube after the tri-lock has overflowed or popped. I decided to add a blow off tube right from the get go. Now my beer looks good in the carboy, I hit my gravity which was 10.60 and fermentation temp is steady between 68-70. I do see a small layer of krausen (maybe 1/2 inch) and also have active bubbling.  I also aerated the beer my shaking and rolling..wish it had been pure oxygen!
 My question is will the larger blow off tube affect the amount of krausen in the carboy?
Thanks in advance

Offline Alewyfe

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Re: Airlock vs. Blowoff tube
« Reply #1 on: November 24, 2014, 06:12:25 AM »
You done good! Many folks user a blow off tube in the beginning then switch to an airlock after the fermentation slows down. Prevents you from blowing gunk into and out of the airlock, or worse yet, blowing it off the carboy and exposing your beer to nasties in the air. . It will not affect the amount of kreusen.
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Offline klickitat jim

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Re: Airlock vs. Blowoff tube
« Reply #2 on: November 24, 2014, 07:33:21 AM »
I cant imagine that it would.

Offline Joe T

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Re: Airlock vs. Blowoff tube
« Reply #3 on: November 24, 2014, 12:05:35 PM »
I use glass carboys or better bottles so I can see the fermentation activity. I've noticed that the increased head pressure from an airlock seems to cause the krausen to rise. When the beer is at high krausen and the airlock is removed, the krausen drops a bit instantly. So it seems to me that the outlet of the blowoff hose in the bottom of a pitcher of water would create a higher head pressure than a few ml in an airlock and might affect the krausen. If the outlet of your blowoff hose is not submerged you will have no head pressure and thus less krausen. The amount of head pressure will also affect ester production.

Offline davidgzach

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Re: Airlock vs. Blowoff tube
« Reply #4 on: November 24, 2014, 01:33:51 PM »
It would only effect the amount of Krausen if you actually had some blow out.  However, this is a good thing as you are also blowing off hop particulate, old yeast and any other nasties that are caught in the Krausen.  Some folks, including Kai I think I remember make it a point to blow off some Krausen in every brew.

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Re: Airlock vs. Blowoff tube
« Reply #5 on: November 25, 2014, 03:09:02 AM »
I think Joe T has a point.  Surface area of the fermenter is a factor, as well.  I notice that my 60L Spiedels have such greater surface area and a very light movement of the airlock that the Krausen is thinner than the krausen in a 5 gallon bucket.  I don't have the physics to justify it, but I notice it anecdotally.
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Offline ngordon34

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Re: Airlock vs. Blowoff tube
« Reply #6 on: November 25, 2014, 06:48:20 PM »
Thanks for all the feedback. I didn't think it was going to be a big deal but I guess I was looking for a little confirmation. Im going to take a gravity reading at day 4-5 after activity has settled down to see where Im at. So if I started @ 1.060 what should I expect to be after a few days? Also Joe T mentioned ester production due to head pressure, is this due to stress being put on the yeast if sufficient CO2 is not released?

Offline Joe Sr.

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Re: Airlock vs. Blowoff tube
« Reply #7 on: November 25, 2014, 09:09:56 PM »
Thanks for all the feedback. I didn't think it was going to be a big deal but I guess I was looking for a little confirmation. Im going to take a gravity reading at day 4-5 after activity has settled down to see where Im at. So if I started @ 1.060 what should I expect to be after a few days? Also Joe T mentioned ester production due to head pressure, is this due to stress being put on the yeast if sufficient CO2 is not released?

Assuming that your airlock/blow off is bubbling and not blocked I don't think you're going to experience a significant amount of head pressure.  I highly doubt that the amount of head pressure in a 5 gallon carboy has a noticeable impact.  Of course, I could be wrong.
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Offline morticaixavier

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Re: Airlock vs. Blowoff tube
« Reply #8 on: November 25, 2014, 10:00:37 PM »
Thanks for all the feedback. I didn't think it was going to be a big deal but I guess I was looking for a little confirmation. Im going to take a gravity reading at day 4-5 after activity has settled down to see where Im at. So if I started @ 1.060 what should I expect to be after a few days? Also Joe T mentioned ester production due to head pressure, is this due to stress being put on the yeast if sufficient CO2 is not released?

Assuming that your airlock/blow off is bubbling and not blocked I don't think you're going to experience a significant amount of head pressure.  I highly doubt that the amount of head pressure in a 5 gallon carboy has a noticeable impact.  Of course, I could be wrong.

Drew reported seeing performance differences with one of the saison strains if an airlock was used over open fermentation. I'm not sure if he ever solidified the findings or not though.
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Offline Joe Sr.

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Re: Airlock vs. Blowoff tube
« Reply #9 on: November 25, 2014, 10:05:10 PM »
Drew reported seeing performance differences with one of the saison strains if an airlock was used over open fermentation. I'm not sure if he ever solidified the findings or not though.

I have to think there's a whole lot of variables there beyond head pressure.
It's all in the reflexes. - Jack Burton

Offline jeffy

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Re: Airlock vs. Blowoff tube
« Reply #10 on: November 25, 2014, 10:45:48 PM »
Drew reported seeing performance differences with one of the saison strains if an airlock was used over open fermentation. I'm not sure if he ever solidified the findings or not though.

I have to think there's a whole lot of variables there beyond head pressure.

Bob at Saint Somewhere reports the same thing: fermentation stalling with any head pressure, even just an air lock, when brewing Saisons.
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Offline HoosierBrew

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Re: Airlock vs. Blowoff tube
« Reply #11 on: November 25, 2014, 11:05:59 PM »
Drew reported seeing performance differences with one of the saison strains if an airlock was used over open fermentation. I'm not sure if he ever solidified the findings or not though.

I have to think there's a whole lot of variables there beyond head pressure.

Bob at Saint Somewhere reports the same thing: fermentation stalling with any head pressure, even just an air lock, when brewing Saisons.

I'm gonna try that the next time I use 3724 - the one Drew referenced IIRC.  Maybe pitch in the upper 60s then ramp up and see if it is more reluctant to stall with no head pressure for resistance. Worst case I can call in the relief pitcher (3711) to finish it up like I have a bunch of times before.
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Offline Joe Sr.

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Re: Airlock vs. Blowoff tube
« Reply #12 on: November 26, 2014, 04:17:07 PM »
Head pressure or none, I've given up on 3724 because its so darn needy.
It's all in the reflexes. - Jack Burton

Offline Stevie

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Re: Airlock vs. Blowoff tube
« Reply #13 on: November 26, 2014, 04:34:28 PM »
Head pressure or none, I've given up on 3724 because its so darn needy.
Yeah. I am a 3711 guy, but I have 1.035 beer that is still chugging along after 18 days. No starter single pack about a week young. I have had 1.065 beers done in 8 days in the past, so I have no idea what the deal is.

Offline HoosierBrew

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Re: Airlock vs. Blowoff tube
« Reply #14 on: November 26, 2014, 04:42:21 PM »

Yeah. I am a 3711 guy, but I have 1.035 beer that is still chugging along after 18 days. No starter single pack about a week young. I have had 1.065 beers done in 8 days in the past, so I have no idea what the deal is.

Using 3724 ?
Jon H.