2.5 gallon batches

I have a 6 gallon glass carboy I use for my 5 gallon batches, but I was wanting to get into doing half batches to try and test some recipes.

Does fermenting a half batch in my larger fermemter increase my chances of the wort getting infected? Has anyone had any issues doing this? Or should I stop being cheap and buy a smaller fermenter?

Me personally it's a worry. I don't go beyond a 5 gallon for 2.5 gallon batches, but even then I'm uncomfortable and prefer using 3 gallon vessels for my small batches, even my old Mr beer keg.

I've done 3 gal batches in 5 gal Better Bottles, but never 2.5 in a 6. I'm guessing it would be ok. My advice would be to never remove the bung or airlock untill you're ready to bottle, and don't let it sit around with that much headspace for too long after fermentation is over. Meanwhile, maybe you can look in to getting something smaller to ferment in.

I have done this plenty of times. There are actually more benefits than worries/costs to ferment a lesser amount of wort in a larger primary. CO2 is heavier than O2. And that extra headspace will create a denser, thicker layer of CO2. The added headspace will also dispel any worry of the beer overflowing. And lastly, you'll have a bunch of extra space for dryhopping with leafs if need be.

I don't see how risk of infection would be more or less with this method. Your only limit would be racking that small amount of beer to a large secondary. You don't want to do that for oxidation purposes. The volume of your secondary should be very close to your actual beer volume.

2.5 is my standard batch size, and I always use 6-gallon pails. This method produces fine beer (so long as I can overcome my propensity to mess up somewhere else in the process). I suppose you would not want to age most beers in such an oversized pail for months on end, but your oversized glass carboy is probably going to admit less oxygen than a properly sized plastic bucket.

I do 2.5 in a 6 all the time, no problems yet.

I also do a few 2.5's in a 6. Haven't had an issue yet (that was carboy caused ). I don't lift the bung, and I sanitize well. I imagine you could just have a longer primary if you really felt the need. The blanket of c02 generated should be sufficient to expel the o2 from the carboy within a few days, and as long as you don't play around with the thing with the bung off you should be fine. Just my opinion...

Hell, I have even no chilled a few 2.5's in a 6.

I like my 3gl carboy for my 2.5gl batches, it's nice and small so it takes up little room, is easier to carry around and clean out. I've seen others do small batches in larger carboys so you should be fine if you don't want to spend the extra bucks on another carboy.

I have a 3g carboy and want to use it for secondary for my 2.5 batches but im to lazy to do secondary so it has not been used lol!

bennie1986 said:

I have a 3g carboy and want to use it for secondary for my 2.5 batches but im to lazy to do secondary so it has not been used lol!

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Use it as a primary for 2 gallon batches. If you don't... I demand you send it to me, so I can!!

Stauffbier said:

Use it as a primary for 2 gallon batches. If you don't... I demand you send it to me, so I can!!

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Lol, ill use it when i have something that needs dry hopped and i need the other primary for a new batch.

Ive been doing 2.5 gallon batches in a 6 gallon Ale Pail for over a year now without any problems.

I share your concern...For the first time I just split a 5 gallon batch of a basic hefe into 2 5 gallon fermenters after a week in the primary. I was a little concerned, but I racked on top of fruit, one on cherry puree and one on a bananas foster mix. I'm hoping that the yeasties will jump on the fruit and push out oxygen, but we will see...

I bought myself a couple 3gal carboys for this purpose. I prefer working with the smaller carboys where I can and in turn I use it for a primary for smaller 2gal recipies.

I just scored a bunch of free bakery buckets. A few 2 gal. and a 3.5 gal. I already had a few of these as it was. I could likely get a couple every weekend when I go grocery shopping.

Small batch brewing is no problem for me. Especially since I don't do secondaries.

But... at the end of the day... I would do 2 gal. in a 5 gal. BB or carboy! I aint skeered!

Stauffbier said:

I just scored a bunch of free bakery buckets. A few 2 gal. and a 3.5 gal. I already had a few of these as it was. I could likely get a couple every weekend when I go grocery shopping.

Small batch brewing is no problem for me. Especially since I don't do secondaries.

But... at the end of the day... I would do 2 gal. in a 5 gal. BB or carboy! I aint skeered!

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If you have good sanitation the size of the fermenter is of no concern. If your sanitation isn't good, the size of the fermenter won't matter much either, you'll get an infection anyway. I regularly do a 2 to 3 gallon batch in a 6 1/2 gallon bucket and the beer always turns out like beer.