Changes

Another less common but occasionally discussed myth about pellicles is that sunlight might cause them. There is no evidence to suggest that sunlight has an effect on pellicle growth in beer. A more probable explanation for pellicles appearing in fermenters that have had sunlight on them is that when the sunlight hits the fermenter, the fermenter warms up. As it cools, a vacuum is created and air is sucked into the fermenter. Mark Trent demonstrates how readily air can suck into a fermenter when the fermenter is cooled (temperature shifts in general and atmospheric pressure changes can cause this):

===Acetobacter===