Adding "new" must to "working" carboy?
1) I have read that the carboy should be almost full. If I am a gallon low, may I start another batch of the same grapes, let them work for a week or so in the primary until the fermentation stops, then rack them into my existing 2 week old must in may carboy to almost top it off?
2) I did not have a hydrometer when I started a batch and now after 5 days I have one and it reads less than 1.000. There are no bubbling noises or any sign of activity. Is it done fermenting? (Blackberries).