Originally Posted by ChshreCat
Temperature stability is JUST SLIGHTLY less important than temperature itself. You want to be at a good temp, but you don't want to be at 72, then 61, then 70.
Also, I'm not sure if I caught if it was actually beer temperature or ambient temp of the room you were referring to. If the room is 61 and your beer is fermenting, then the beer itself is likely in the neighborhood of 65 or 66.
Some good advice!
You really don't need all of these temperature swings. Just put that beer in an area that is close to the temperature you want to ferment at and let it slowly warm back up. You certainly don't need a space heater or anything like that.
I also don't agree so much with that comment on the fermenter being a lot warmer than water in a tub. Water is really good at pulling heat away from the fermenter, I can't imagine the temperature of the beer being much more than a degree warmer than the tub water even at the height of fermentation. Maybe if the water is in a room with a high ambient temp or the fermenter isn't submerged more than a few inches. If you can control the room temp and/or water in the tub temp you will also control the fermenter temp pretty closely and also keep things stable.
You may even want to let the beer get up to 70 after 5 or 6 days of fermentation if you are looking to dry the beer out some. I'm guessing you are using Safale S-33 which may finish at a pretty high gravity if you are at 60 degrees.