So I' resisted my previous urges to ask questions that have probably been asked a thousand times before, opting instead to search and read as much as possible. However I just experienced something tonight that I haven't read anything about and want to know if this is normal.
I brewed my first batch this past Saturday, and Irish Red Ale extract kit from Northern Brewer. All went well, I prepared a yeast starter several days ahead of time, pitched a large amount of yeast and I saw signs of fermentation within about six hours. Fermentation has been steady for the last few days.
I'm storing the primary in a closet that is right at 73F, so I'm holding it in a cooler with water in it to bring the fermentation temp into the mid 60s. SWMBO has been complaining that she's cold at night so the heater is getting turned up tonight, so about 2 hours ago I added a single 16 oz frozen water bottle to the cooler to keep the temp in the primary from rising. There was a very nice thick krausen at the time. I just went to remove the water bottle and much to my surprise, the entire krausen has dropped and disappeared. Fermometer is reading right at 65, it was about 67 before I added the frozen water bottle. Is the drop of temp a couple degrees what caused the krausen to disappear? Or is this a normal part of the fermentation cycle?