I have had a batch in the primary for 1 week as of today. It is set in a large styrofoam cooler with extra insulation I had from insulating our crawl space placed in the void in the cooler, then wrapped with a few towels where the fermenter comes out. I cut a hole the diameter of the fermenter in the lid, so it sticks out a bit. Anyway, it started out around 68 and held there for a few days, between 66 and 70. Since the beginning of the week, it’s been in the 30’s at night and this room gets kind of chilly. I’d guess in the 50’s perhaps. I’ve been checking it daily to make sure it didnt get too low or too high and the beer has been around 60-62 judging by the LCD strip thermometer thing. However today, a heater was accidentally turned on in the room, and when I got home, I checked the temp as it seemed warm in the room and it was at 77. Quite a change. I’m thinking it will be okay given that its been a week already, and I plan to leave it alone but just let it slowly get back down to the mid 60’s. I am planning on leave it in primary for a week, then in a secondary for two weeks for a dry hop, then bottle.
Any input? At what point is it okay to let the beer go below the optimal range for fermentation for the yeast?