Odinperez

Recipes 

I would like to know your opinion about what could go wrong in fermenting 3 gal batches of beer in 5 gal carboys. I'm intending to do this because I don't want the krausen to get out of the air lock and all that kind of problems I have had sometimes when there's a lot of krausen forming, I know this is depending on the style, but with stouts I have allways had this problem.

Thank you!

lowtones84

Recipes 

I've fermented 3 gallon batches in 7.5 gallon buckets as well as a 6.5 gallon carboy. It was only primary though and I tried to keep it fairly short (2-3 weeks). So far I haven't noticed any problems despite the massive head space.

gbx

Recipes 

I split most of my 5gal batches between 2 6gal better bottle carboys. It works awesome.

Gavagai

Recipes 

1. Do it. Lots of headspace is no problem in primary.
2. Your only concern is krausen? Have you heard of a blow off tube?

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Grantman1

Recipes 

I ferment 3 gal batches in a five gal carboy all the time, and never had any krausen close to the top. But if you're still worried, you could use a blow off like the post above mentioned.

Odinperez

Recipes 

Thank you all for sharing your experiences. This information is very useful to me!

Calichusetts

Recipes 

Better yet...brew 3.5 gallon batches in a 5 gallon carboy. If you need to secondary (fruit, oak, dry hop, etc) you can get a 3 gallon carboy and completely fill it, no worries of headspace and oxygen

bobbrews

Recipes 

Excess headspace in the primary is a non-issue... in fact, there may be some added benefits, one of which includes a thicker/denser 02 blanket to protect the beer. Excess headspace in the secondary however is certainly an issue.

Hopper5000

Recipes 

I've done it plenty of times with no issues (im doing 3.75 gal). Only tricky part is getting a gravity reading/sample as my theif is barely long enough.

brewfreeordie

Recipes 

I could see it being a problem in the secondary if the batch is pretty much fermented out, but there's so much CO2 being pushed out the airlock it must be completely blanketing the wort. I could see if you move your containers around a lot, but if you don't invade the space I don't see a problem.