Author Topic: Carboy headspace size  (Read 771 times)

Offline NeverTooBitter

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Carboy headspace size
« on: December 10, 2015, 05:59:55 PM »
I'm going to be doing some small batch brewing (1 gallon) to refine some recipes.  So I recently picked up some 1 gallon glass carboys.  Upon filling them to measure where 1 gallon of liquid fills to, I noticed there is not much space left for CO2.

https://goo.gl/photos/T6et1bwxx5osxm656

As you can see, there is a small amount of space left.  This measures to approximately 1 cup of liquid.  sorry for the link.  I'm having issues embedding the image here.

My questions are:

Is this enough space for fermentation?  I'm assuming not.  If not, would using a blow off tube make it work? 

How much space should there be left?

Any input/suggestions here would be appreciated.
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Offline Stevie

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Re: Carboy headspace size
« Reply #1 on: December 10, 2015, 06:08:01 PM »
I'd say your fine with a blowoff.

Offline Slowbrew

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Re: Carboy headspace size
« Reply #2 on: December 10, 2015, 06:10:50 PM »
It might work okay.  It depends on the yeast and fermentation temp.  If you are using vigorous strain and fermenting warm you will need deal with a lot of blow off.

The neck is quite long so you may gain a bit there.  Fermenting on the lower end of the temp range and keeping your OG low could keep most of the krausen in the jug.

That's an awful lot of "it depends" type answers but all I've got today.

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Offline stpug

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Re: Carboy headspace size
« Reply #3 on: December 10, 2015, 06:11:04 PM »
I recently used a 1G carboy (juice jug really) but only filled it to 0.85 gallons. This left enough headspace that most of my batches would survive without any blowoff, but any large krausen beer could still blowoff. I happened to have a large krausen that was threatening blowoff so I added an ounce of boiled water with 2 drops Fermcap-s to the carboy to keep the krausen at bay (worked very well).

The ideal size for 1 gallon batches would be a 1.25 gallon vessel.

Offline NeverTooBitter

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Re: Carboy headspace size
« Reply #4 on: December 10, 2015, 07:50:24 PM »
It might work okay.  It depends on the yeast and fermentation temp.  If you are using vigorous strain and fermenting warm you will need deal with a lot of blow off.

The neck is quite long so you may gain a bit there.  Fermenting on the lower end of the temp range and keeping your OG low could keep most of the krausen in the jug.

I'm planning on doing a brown ale with an OG of 1.054 and an IPA with an OG of 1.074.  The room I will be fermenting in rarely gets above 65-67 degrees.
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Offline coolman26

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Re: Carboy headspace size
« Reply #5 on: December 10, 2015, 07:53:11 PM »
You could always use a little Fermcap too
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Offline IMperry9

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Re: Carboy headspace size
« Reply #6 on: December 11, 2015, 08:57:17 PM »
What I do when brewing one gallon batches is for the first couple days after brewing when its in the most active part of fermentation use a blow off tube into a bowl of sanitizer. Then once it slows down I put a airlock on there and let it finish out and I have never had problem.
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