I tried this and got good results but very very dry. I am a huge Apfelwein fan after living in Germany for a couple of years, so although I like the way my batch turned out it seemed to be missing the tartness of Frankfurter Apfelwein. I talked with the guys at my local brew store and they told me that the tartness would need to come from the juice. So I am going to try an experiment. . . I have some jonathon apples just getting ripe and I am going to juice them and try a mix of fresh juice along with the bottled stuff (I don't have the bushels of apples necessary to produce 5 gallons of juice). Hopefully this will boost the tartness I am striving for.
Any thoughts?
Also could anyone suggest how much additional sugar to add - for example how much sugar is in the bottled juice; if I use a 2:3 ratio two gallons tart juice to three gallons bottled juice, how much more sugar should I add to get the fermentation I want?