I've had this problem ever since I started using my new fermentation chamber made from a 6 foot chest freezer. I've drank 15 gallons of beer that has had this on it and they all came out great.... I recently started using Starsan instead of OneStep to ensure it's sanitized, but I just transferred this last week, and here we are again with this skim on top of the beer. Any ideas as to what it may be?