I have a 6.5g bucket and a recipe for 5 gal. I decided to add some extra malt to bring it to 6 gallons (mistake) Anyway, a day later it had foamed up enough to clog the air lock and blow the top. I cleaned the lid and airlock and replaced it, noticing that the foaming had dropped to about 4 inches from the lid. I assumed that the violent initial fermentation was over since the foam was subsiding. After the lid was replaced for about 2 hours, i noticed discoloration in the airlock water and removed the lid. Sure enough, it had foamed back up to the top again. I set the lid back on without sealing it to avoid another small explosion.
My question is, why did it foam up a second time? I assumed it foamed up alot in the beginning b/c the yeast is all excided with the sugar and what not, but once the foam dropped, i assumed it was slowing down. Does it ferment in stages? Does the lid being off slow it down? What gives? I would assume that since it had a day to produce alcohol before being exposed to the open air, the chance of contamination is much less; is this the case??