also the must level has rises in the demijohn. when i started fermenting it was at the base of the neck if not abit below that. now it is 1 inch high up the neck of the demijohn. how is this possible i never saw this on my ancient orange batch, is this another trait of the blueberries or is it because im using an airlock. i must admit the fermentation is much more vigarous than it was before, bubbling at twice the rate as last time. i did how ever add some yeast nutrient. i believe i have added 1 gram which is what i was trying for.