Brewed a sweet potato/pumpkin pie spice ale on Sunday. 5.75 gallon batch with a starting gravity of 1.061. Cooled to 66 degrees f, oxygenated with pure O2 and 0.2 micron diffusing stone for 30 seconds. Pitched one 11.5 gram package of S-04 without rehydrating and shook a little to get the yeast mixed in. Attached blow off tube. Temp controlled fermentation set at 67 degrees f using swamp bucket, t-shirt for wicking and a fan attached to a temp controller.
Monday morning there were some signs of fermentation (movement in wort and krausen beginning to form), however, no off gassing through blow off tube. Monday evening large krausen coming up neck of carboy but did not reach the blow off tube. Still no off gassing through blow off tube. I got worried I had a leak in the carboy cap, so I used parafilm to make sure I had a good seal to the carboy and also parafilmed the blow off tube connection and the other small white cap. Even after sealing everything up, still no off gassing. Last night, 48 hours after pitching, krausen had reduced significantly, still no off gassing evident. I decided to replace the blow off tube with a three piece airlock and watched for 10 minutes. Not even one bubble. At this point I removed the carboy from the swamp bucket, pulled back the t-shirt and tilted on its side. An amazing amount of bubbles, presumably CO2 started coming out of solution when I did this, but to my amazement, still no airlock activity. I've got three thermometers on this fermentation, the Johnson digital controller, an aquarium thermometer on the carboy itself and a traceable mini that is continuously on and logging high and low temps. So far, all three thermometers are in close agreement and the ranges logged by the traceable is 66-68 f.
I know airlock activity isn't a surefire sign of fermentation activity, and usually I don't worry, but I've never seen a fermentation that didn't produce at least some off gassing. Thoughts?