I had a similar thought, about using a 6 gallon carboy to brew 5 gallons of 'second ferment' kombucha in it. Not keeping the SCOBY in the jar, but putting the already fermented kombucha, you would otherwise bottle, into it and using some kind of single or twin Bubble Airlock with a carboy bung? Or some sort of cap that you could periodically release the gas, during the second ferment? Then transfer it into individual bottles, AFTER the second ferment is complete.
I just thought my entire batch of flavored kombucha would have consistency; flavor, body, effervescence.
Anyone ever try this?
What other apparatus did you use?