Secondary carboy size questions

I'm getting ready to start my next batch this weekend and am planning on a blonde ale which I will split in two after primary fermentation. One half will become a blueberry blonde and the other will be a raspberry blonde. I want to add the fruit to the secondaries, but I'm not sure about what size carboys to use. I've got two 3 gallon carboys which I was planning on using, but after reading other posts, it sounds like I should expect secondary fermentation to take off.

• Beer+fruit won't leave much room in the 3 gallon carboys, so should I move up to two 5 gallon carboys instead?
• Will the head space still get filled with enough CO2 to prevent oxidation?
• If the 5 gallon carboys are too big, could I fill the head space with that wine saver gas (I think its just nitrogen and argon)?

I'll be using Oregon Fruit Products canned fruit (not the puree).

there should be enough there. Someone once calculated (and I think posted on hbt) that a typical 40grav beer would put out something like 600 gallons of CO2, displacing most of the original air.

Anyhow, the fruit should have atleast 10% the sugar conversion that the original beer did, so call that 60 gallons of co2 generate and >> greater than the 2 gallons of head space. (10% sugar= wild end guess btw, I'm betting it would be higher).

I'd say you should be find doing it that way.

5 gallon carboys should be fine

You should be fine with the 2-3 gallon carboys. The secondary fermentation will be so minimal that even though it is there, you won't have anything to worry about. (At least I don't think you will have anything to worry about) The air lock will let out any extra gas and if any krausen does form, it will be EXTREMELY negligible. Good luck with the 2 beers.

Thanks for the replies!

I went ahead and got a couple of 5 gallon carboys from AHB (the cheaper BB knock-offs) and will use those for secondary. That way I can use the 3 gallon ones for tertiary. Good to know the amount of CO2 production though.

I might be wrong, but I would keep my eye on the carboys, because adding furit is going to kick the yeast into gear again and start fermentating again because of the sugars. You might want to use a blow off tube just to be safe.

+1 I did a cherry wheat (5 gallon) in a 6 gallon carboy with no issues. Split into two 3's should be fine.

Shaneoco1981 said:

You should be fine with the 2-3 gallon carboys. The secondary fermentation will be so minimal that even though it is there, you won't have anything to worry about. (At least I don't think you will have anything to worry about) The air lock will let out any extra gas and if any krausen does form, it will be EXTREMELY negligible. Good luck with the 2 beers.

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