I recently fermented a batch of beer (5 gallons) in a 7gal carboy, which left about 2 gallons of space above (assuming you filled it all the way to the top). I also have a 5gal carboy, but that would be 5 gallons if I filled it all the way to the top.
My question is, if I am going to brew 5 gallons of beer, how much head space should there be? Here are the options I see,
- Fill up the 5gal carboy, and leave a little bit of space in the top
- Buy a 6gal carboy, and fill it up to 5 gallons.
- Use the 7gal carboy, and fill it up to 5 gallons.
- Use the 6 or 7 gallon carboys, and fill it up over 5 gallons.