Made a batch that was too large to fit into one carboy, so I put 3.5 gallons in one carboy, and 3 in another. Pitched a starter of Wyeast 1335, and fermentation started strong after 12 hours. Continued strong for 48 hours with both carboys fermenting at the same rate. After 48 hours the krausen dropped on the one carboy, but not the other. It's been 6 days, and the one carboy still has 4 inches of krausen, still fermenting, and the other has been pretty much done for 4 days with only a few bubbles.
What's the deal? Did I maybe get more yeast in one than the other? They've been at the same temp the entire time. I'm planning on waiting till the one is done, then checking the gravity of both. What would make one would take so much longer than the other?