I'm bottling my first Mr. Beer brew, or any brew for that matter, tomorrow and I just left it in the fermenter for two weeks. At that point I figure it should be done fermenting. With mine I was able to observe an obvious fermentation through the keg and could see it falling out a few days later. Now, when I shine a light into the side it looks nice and clear. Well, other than all that stuff collected at the bottom, but that's to be expected.