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2.5 gal batch in 5 gal fermentor

Hi all,

I’m just getting into homebrewing and due to space restrictions I wanted to brew smaller 2.5 gallon batches rather than 5 gallon.

From what I have heard, I should be ok cutting a recipe kit in half, but my concern is the size of the carboy.
Does anyone see or has anyone had any issues fermenting a smaller batch in a 5 gallon carboy? I thought that I had read somewhere something about leaving too much space between the liquid and the airlock. Or should I invest in a 3 gallon carboy?

Any thoughts?

You’ll be fine with a 5 gallon fermenter. The headspace will quickly fill with CO2 once the beer begins to ferment, thereby protecting the beer from oxidation.

You’ll be fine fermenting in a five gallon carboy, I do it all the time. The fermentation will push all the air out and replace it with CO2. You only need to worry about headspace if you’re transferring to a secondary. You can use a 3 gallon carboy for that, but lots of people don’t bother with secondaries.

agreed with that last two posts about the CO2 pushing out the oxygen…I’m curious how much yeast you plan to pitch and how you will go about it? I would guess that you could simply dump a portion of the yeast in and toss the remainder…but still curious.

Agreed, there’s no problem with the 5 gal container, but you might consider this: ... facetInfo=

I just bought two of these, I’m going to use them on Sunday.

I pitch the same amount of yeast in a smaller batch that I do in five gallons, unless I’m pitching slurry.

Yeah, I hadn’t gotten that far in my process to figure out how much yeast I would plan on using. This will be my first batch.
Good to know that 'Rover has had success pitching the same amount of yeast. Unless I read anything else I will give that a try!

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