2.5 gallon batch question

[homebrewmike]

I'm looking at doig a 2.5 gallon batch of coffee stout for my sister in-law's 21st and was wondering if I can get away with putting it into a 5 gallon carboy to ferment? A 3 gallon carboy doesn't seem like it has enough head space to allow for any krausen. Thoughts?

 

[thadass]

Absolutely. I've done several 2.5 or 3 gallon batches in a 5G carboy. Just be sure to not let it sit around for months or shake it before bottling and you'll be fine.