Okay, I left the OG sample from my last batch in the hydrometer and a couple days later I noticed it had foam on top and yeast churning in it. The gravity had gone down also. I left it alone and it was down 30 points in 4 days without adding any yeast. I know yeast is in the air everywhere but my house must be full of it. I know there is no way to know what types of yeast will prodominate,but it is an experiment. I think I wll just cover the fermenter with cheesecloth to keep out bugs, hair, etc. but let yeast in. Any suggestions on recipes or techniques?