Fermenting in oversize Carboy

[marvso]

I recently acquired a couple of 2 1/2 gallon corny kegs (for free). I have been brewing 5 gallon batches. I would like to split a 5 gallon batch in two and use different yeasts in each batch. I have several 5 gallon glass carboys and don't really wish to purchase smaller carboys. Any problems fermenting in a 5 gallon half full, or half empty?

 

[twistr25]

Shouldn't be too big of a deal for a primary. Definitely would not recommend for secondary.

Prolly won't need a blowoff setup

 

[mChavez]

I'm only a beginner, so I might be wrong, but I'd guess that Co2 will fill the extra space so there should be no issues there.

I was thinking of splitting batches myself, so would like to see what the pros say.

 

[evrose]

I primary 2 gallon batches in 5 gallon buckets all the time. Works great... no need for a blowoff tube (bonus!).