This is why I do a carbonation test bottle for each flavour...
I use soft sparkling water bottles. Fill them to about 3cm from the top. Squeeze out the excess air. And seal it.
As the kombucha carbonates, it's slowly fills the bottle back out. When the bottle is nice and firm, I know the brew is ready.
The first pic is immediately after bottling, the second is about 10hrs later, and they're all at different stages.
The strawberry bottle has already popped back into shape. It's not firm yet, but I wouldn't be surprised if it is by tomorrow morning. And the mango is a little further along than the pineapple, but not by much.
Carbonation relies on sugar content. The kombucha feeds on the sugar and converts it into C02. So generally, fruits with a higher sugar content will make the kombucha carbonate faster. Which is why each flavouring carbonates at a different rate.
