I have just brood a batch of Ginger beer with keviak yeast. I gave it Yeast Energizer and yeast nutrients. I use Firmaid O. And the 1st day it went well but the 2nd day when I add some more from aid O, the fermentation was erratic. It has not been consistent for the last 2 days sometimes it's superfast. Sometimes it's little slow. At first it started to go really fast with a little slow burst and then fast again. I have prude for more than 20 years but I never had this problem.