3 gal. in a five

[berryman]

I have really been thinking of doing some smaller batches, but here is what I have for fermenters, 4 LBK's, 3 - 5 gal carboys and a 7 gal. Ss brew bucket. I really don't want to go back to the LBK's and it is hard to do a 2.5 in them anyways, but I would like to do a few 3 gal so I can try a full volume mash. So here is my question, do you think using a 5 gal carboy on a 3 gal batch would be to much headspace? I do 5 and 5.5 in the 7 gal and sometimes on bigger beers need a blowoff in the beginning on that. I am thinking no problem, but would like others opinion.

[mashani]

The 3 gallon fermenters I use are actually 4 gallons if you count the headspace.

Coopers/Mr. Beer sell them for making 2 to 2.5 gallon batches which are then pretty much guaranteed to not ever blow off.

I've made plenty of 2.5 gallon batches in them without issue, and they aren't even airlocked, so that's 1.5 gallons of headspace.

People use 6.5 gallon carboys for 5 gallon batches too, so that's also 1.5 gallons of headspace.

I don't see how 2 gallons of headspace in an airlocked fermenter is all that much different then 1.5 gallons of headspace in my non-airlocked fermenters.

I think you will be fine. I think it would be more of an issue if it was being used as a long term secondary fermenter. But don't think there is one as a primary.

[berryman]

People use 6.5 gallon carboys for 5 gallon batches too, so that's also 1.5 gallons of headspace.

And that has been what I had been doing right along for quite a while and now use a 7 gal with 5-5.5 and sometime six gallons, so I know that does work. Just looking for some reassurance before I do this and pretty much sure no problem and some topic talk to wake up the dead, and generate some discussion and reassurance is very good also

I don't see how 2 gallons of headspace in an airlocked fermenter is all that much different then 1.5 gallons of headspace in my non-airlocked fermenters.

Yup I agree

I think it would be more of an issue if it was being used as a long term secondary fermenter. But don't think there is one as a primary.

Yes and also agree on that. I would also not do it on a secondary, but not doing secondary anymore, except on my last lager and when I did I liked to have the secondary filled most of the way to the top.

[Kealia]

I have done this many times without issue. I used to have a 5 gallon glass carboy and I would sometimes do a two and a half gallon batch in it. You still get airlock activity meaning that it seems apparent that all of the headspace will be taken up by CO2. I think at some point somebody even did the math to figure out just how many cubic feet of CO2 is produced but I won't go into that detail.

So the short answer is, yes you will be fine.

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[John Sand]

Same here. I have a half batch merrily bubbling in a 5gal carboy right now.

[Dawg LB Steve]

I see no problem. Primary doesn't matter on headspace as the co2 creates enough pressure and volume fill that space. Secondary does matter because of lack of fermentation activity. I do 5 g batches in my 8 g buckets.

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