How cold is too cold

DDQ · May 30, 2012

Have an IPA in the fermenter, it's day two. I have it in a water bucket with a wet t-shirt over it. The kit says ferment at 68-70 degrees, this morning I measured it at 64. I know the yeast can slow down with lower temps, but is this too cold? Wondering if I should take away the t-shirt and just let it be at 72 house temperature.
Thanks for any comments!

chezteth · May 30, 2012

64 is fine. After 4 or 5 days let it warm up to make sure it ferments out completely.

Pie_Man · May 30, 2012

64 is probably just fine although it does vary between yeast strains. Do you know which yeast you used?

Also, how are you measuring temperature? Are you measuring the ambient air, or the temperature of the beer? In my experience, the beer tends to ferment about 5-10 degrees warmer than the ambient air temperature when at, or near, high krausen.

DDQ · May 30, 2012

The yeast is Saf Ale US-05. I'm measuring the temp of the water the fermenter is sitting in. So if the wort is 5-10 warmer, it's 69-74? So I'm close to my 68-70 target. Maybe a little warm.
Thanks for the feedback!

rodwha · May 30, 2012

I don't believe your wort will get 5-10* warmer than the water it's in. Maybe a couple of degrees.
I shoot for 64-66* (water temp) with my brews as most of the yeasts claim optimal temp is mid-high 60's. I'm ordering a fermometer so as to be able to check actual wort temp...just so I know...
I think your beer is fine at that temp.

Pie_Man · May 30, 2012

Sorry, I forgot you were using a water bath to maintain temperature. I've not used that method, but I would think the beer and water temperatures would be roughly equal. Without a water bath, you'd get a noticable temperature difference.

I've found that US-05 yeast is pretty hardy, you're fine at 64F, a few degrees warmer would also be fine.

daksin · May 30, 2012

I ferment US-05 pretty much at 62 exclusively. 64 is great.

gcdowd · May 30, 2012

Agreed, mid 60's is range I use with 05.

hops2it · May 30, 2012

I have an ale going right now at 64-65 in the fermentation chamber. Personally, I like this temp range for US-05. I've had a few that turned out a little on the dry side when going much higher. Then again, maybe I was a few degrees high on the mash on those beers but ever since its become my standard.