2.5 gal batch in a 5 gal fermenter

The title explains my question really. I have a 2.5 gallon recipe but only a 5 gallon fermenter. Is this a problem?

 

I also have three 1 gallon fermenters. The same question applies. Does a half a gallon in a 1 gallon fermenter work?

 

Do it. No problem. I have a 3 gallon batch in a 5 gallon carboy right now.

 

Nope, not a problem at all, I do it all of the time without issue. The only time it would be a concern is if you were to have that small of a batch in secondary...but for primary it's just fine.

 

Why is it bad for the secondary

 

An enormous amount of CO2 is produced during primary which flushes all of the air in the headspace out and replaces it with CO2 which prevents oxidation of the beer. If you secondary a beer with that much headspace then there's not really much more CO2 coming off the beer so the air in the headspace won't be flushed out, which will lead to oxidation.

 

And oxidation produces off flavors? Will it still be drinkable. I've done exactly that with a beer I put into 3 separate secondaries with different flavours. Eg. Oak chips, cocao nibs etc? Is it all ruined do you think

 

I just bottled it last night actually.

 

Yeah oxidation produces stale, cardboard, and/or sherry like flavors. Once fermentation has begun you want to minimize the amount of oxygen that the beer is exposed to. This is why you gently rack the beer to move it instead of pouring, and it's why if you use a secondary you need to minimize the headspace. A lot depends on how long you left it in the secondary. You might be ok, I'm not really positive on how long it takes for oxidation to set in. I think you'll just have to wait and see and learn for the next batch. Good luck!

 

I always flush any secondaries, transfer equipment, kegs etc. with CO2 before transfer. Of course no secondary is airtight so eventually O2 will seep in and cause oxidation over time. Normally I don't have anything in a secondary very long(I don't use them unless I'm adding oak, fruit, spirits, or with sours) except with my sours which can benefit from a small amount of Oxygen.