I'm new to fermentation, and I just recently started fermenting a number of different juices in parallel: Martinelli's apple juice, grape juice, cherry juice, pomegranate juice, and peach juice. I started them all at the same brix level, and am using the same Premier Cuvee yeast in all of them. What's noteable is that the bubbler on the Martinelli's has been going probably 2x the speed of the next fastest (grape) for the same volume of liquid. Is there something about apple juice (its Ph or maybe some thing else) that makes it far more favorable to rapid fermentation than the other juices?