What is the second ferment for? Do I have to do it?

The second ferment is done in a sealed bottle to allow carbonation to develop.

1. During the first ferment the kombucha is able to breathe and all gas produced will escape, your kombucha will be flat.
2. The second ferment traps the gas in the kombucha so there are bubbles when you drink it. It is also a chance to add flavours or infusions.

You don't have to do the second ferment, the kombucha is still just as good for you after the first ferment. We recommend a shot of kombucha from day 25 of the first ferment in a glass of sparkling water if you still want the bubble.