Does anyone else do this? I put a clear plastic cup over my airlock to capture the escaping co2 and aroma. I don't pay much attention to my airlock as far as a fermentation indicator, but I do pay attention to the smell coming out of the airlock. Sweet/molasses smell and fermentation hasn't done much yet.. Nice beer smell and I know some amount of fermentation is taking place. It's not a science by any means, but it is a basic indicator for me. Plus I just love to smell the cup.. It's the sweet smell of success!