2.5 gallons in 5 gallon carboy

I am fermenting a half batch in a 5-gallon carboy. I figure due to the nature of fermentation and CO2 most of the air has been driven out of the head space.

If I plan to do a clearing rest should I try to get something smaller to minimize the contact with air to avoid oxidation?

I want to age long in bottles, so I want to reduce oxidation risks as much as possible.

It works fine I've done it many times.

petep1980 said:

If I plan to do a clearing rest should I try to get something smaller to minimize the contact with air to avoid oxidation?

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I wouldn't secondary a 2-1/2 gallon batch in a 5 gallon carboy. Too much head space and like you said, chance for oxidation. If I wasn't doing any additions that had to be done in a secondary, I'd just leave it in the primary for a week (more or less) after it reaches final gravity, then cold crash and bottle.

AnOldUR said:

I wouldn't secondary a 2-1/2 gallon batch in a 5 gallon carboy. Too much head space and like you said, chance for oxidation. If I wasn't doing any additions that had to be done in a secondary, I'd just leave it in the primary for a week (more or less) after it reaches final gravity, then cold crash and bottle.

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That was my original thought process. Thanks.

I do this often, but i do squirt a bit of co2 in the carboy to purge some oxygen out of the headspace.
Never had an issue.

+1 to just about everything above. I do this often, but I secondary in a 3 (2.5?) gal better bottle. It's a great way to get a ton of yeast going before a big brew.