I recently added an STC-1000 to my deep freeze for a fermentation chamber. I set it at 65 degrees and put two buckets in with a Fat Tire and a Crooked Tree (all grain clone recipes), one with dry yeast and the other with a smack pack. I checked on them after a couple days and didn't notice any bubbling in the air locks but they were the first day. So, I pressed on the lids like I did before I had the fermentation chamber and the smell was horrible and burned my nose. From what I've researched it's just the co2 correct? Did I always have this before when I just left them on the basement shelf and didn't notice because it wasn't in an enclosed space? I peeked into the Fat Tire and it looked normal. I did the batches just the same as before and sanitized with Star San. Vodka was used in the air locks both times.