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Does it have to be a 6.5 gallon carboy?

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rockydog101

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Hello. Most extract kits I have used recommend a 6.5 gallon carboy. I only have one. But I have multiple 5 gallon carboys. Most beers I've brewed have an inch of two of krausen. Any reason I can't just use five gallon carboys for primary fermentation?
 
If you have two 5 gallon carboys, you can. Just split the wort contents between them both as well as your yeast. The reason you would want a 6.5 gallon carboy to ferment 5 gallons is so that there is head-space to allow for oxygen and room for krausen. If you fill up one 5 gal. carboy with all of your wort you will not have sufficient head-space which will cause some headaches.
 
Keep in mind that your inch or two of krausen is spread out over the entire area of the largest part of the 6.5 gallon carboy. Filled to the neck, that foam is going to have nowhere to go but up.
 
i'm planning a five gallon kit in a six gallon carboy ...

... is it better to split it into two three gallons ( i'm a wine maker mostly, new to beer ).
 
My buddy has done 5 gallon kits with his 6-gallon Big Mouth Bubbler as a primary, but given that 1/2 gallon less of room to spare, I would do my best to keep fermentation temps as low as possible for the yeast strain and keep a blowoff tube handy just in case.
 
You could always use 2-3 drops of fermcap to minimize the amount of loss you'd get through the top. Either way, use a blowoff tube for sure
 
Use a large blow off tube and you can use the 5 gallon carboy's. You will loose some beer to out the blow off depending on how vigorous the fermentation is. Once the fermentation dies down you can put a airlock on and things will be fine.
 
I used a 5 gallon carboy for five gallon batches for a year. That said it does work you have to accept the fact you will have some loss wort thru a blow off sometimes quite a bit. I always used a Blow off tube and needed it. My losses averaged 1/2 a gallon. :(
 
I used a 5 gallon carboy for five gallon batches for a year. That said it does work you have to accept the fact you will have some loss wort thru a blow off sometimes quite a bit. I always used a Blow off tube and needed it. My losses averaged 1/2 a gallon. :(

That makes a lot of sense actually..because as the yeast floculate, they are reproducing and taking up volume in the carboy, not to mention as they do so they are also giving off gases which are competing for space as well...simple physics explains what happens next...:D
 

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