I like to use chopped fresh ginger to flavor my kombucha for a second ferment. THe jar I use (almost a gallon) makes 5 bottles. THe last two batches, two of the bottles have fizzed up really nice ad the other 3 have been flat. What would cause this? Same amount of ginger, kombucha and headspace in all the jars. After the first batch did that I set the second in a different place to finish.