Welcome to the legal labyrinth that is kombucha!
Some resources to consider looking into to determine what your state requires:
- Department of Agriculture
- Health Department
- Secretary of State (if you are creating a business)
I would do some research on your state's Cottage Food laws. I am...
I highly recommend getting an accurate pH meter so you can put a number to your fermentation process vs. just tasting.
Also, don't skimp on starter tea, it will speed up the initial ferment and reduce chances of contamination.
All the nutrients should be there, adding a bottle of GT's might get it going. Maybe let the GT's get to room temp before adding it so you don't shock the cultures.
Acetic acid is produced by the bacteria during the fermentation. To me it seems the hydrometer isn't accurate because it is suggesting that the sugar isn't being consumed by the yeast either with how little your numbers changed, but you saw CO2 bubbles so the yeast were likely active.
Your...
How exactly are the last 3 gravity readings useful? After a 5 day fermentation your gravity dropped by 0.002. What does this tell you?
Your pH after adding starter tea is 3.8? How much starter tea is that?
Very interesting data here!
I agree, batch brewing is the way to go.
Regarding your kombucha becoming too vinegary though - that is what happens. It's the natural process of making the drink and acetic acid is an end result.
If you want to keep doing continuous brewing, draw more kombucha out of the pot each time...
Try adding a cup of distilled white vinegar to the tea. It sounds like neither the yeast nor the bacteria are currently active. The pH spike might get the bacteria going and in turn the yeast.
Do you know what temperature your fermentation is at? Does it remain consistently at that temperature?