The temp probe in the thermowell in my Unitank came out after a day or two of fermenting a German Pils with 34/70 yeast. I wondered why the bubbles slowed down. Gravity was at 1.030 after 6 day, another clue something went wrong. I heard this yeast is amazingly robust and can ferment at temps close to freezing. When I inserted the probe all the way in it dropped to 39F, from 50F. My target was 48F. The probe didn’t fall all the way out so it was half room temp / half beer temp and the glycol just kept on running. I’m letting it free rise to 48 where the glycol will kick back in. So many questions but the main ones being: 1) Will it reach terminal gravity or will the yeast crap out? (FYI: I pitched a big 4L starter). 2) Will this affect the flavor either negatively or positively? I really want this beer to turn out since I put a very long day in of step mashing and decocting and hit all my numbers. Thoughts?
I think you’re OK on all fronts.
That seems a little too cold in my opinion. I’ve known 34/70 to ferment at 50f but their recommendation is at least 53f.
The colder it is the slower it will ferment. You will get a clean fermentation profile at lower temps (with it’s signature touch of acetaldehyde) but i’d imagine 39f would cause it to go dormant. I would warm up the tank, and rouse the yeast. With a unitank, you could hook up co2 to the bottom port and give it a few bursts.
Warmed up to 48 and fermentation picked back up…still bubbling at day 10 and gravity is 1.014. So far so good. Thanks for the comments Denny and Kev!
34/70 would in all likeliness ferment below 45* regardless of manufactures range. I would bet money it would ferment to terminal below 40* but obviously that would add time to the ferment. Not truly knowing how low your ferment reached it is still a testament as to the viability of yeast. I may have to try 34/70 below 45*. I often ferment it at 48* my self.
Cheers!
I’d like to see kveik do that!
Truthfully, almost any yeast will ferment at that temp, or lower, albeit slowly. That’s why you have to be careful when you store yeast slurry in the fridge.