I started making this apple and ginger wine. I am making 2 gallons. I am using Gervin GV4(26) yeast strain. I heard it can produce a lot of alcohol. Anyway, the fermentation slowed right down to nearly 4 minutes between bubbles, then when thought it was done, it kicked off again st 2 per minute. Now my question is this: when will o know when the fermentation is well and truly finished?