Our neighbor Rindon brought over frozen pureed blackberries and raspberries that he strained to removed the seeds. We used this to flavor the large batch 1/3 cup of blackberry (or raspberry) plus a tablespoon of sugar. We made 8 bottles of raspberry and 7 bottles of blackberry.
We pulled the raspberry and blackberry after two days. Was not explosive, the raspberry had enough fizz and was delicious, however, the blackberry was flat but tasted really excellent.
The medium batch was also strong so we used 1/2 tablespoon to each bottle. We made 8 bottles.