Understanding Yeast Fermentation Temperature Ranges

[asg816]

Hey everyone! I’m really new to home brewing: I’ve brewed twice with others and I just set my first solo batch in the basement to ferment 3 days ago. Two more days til I add the dry hops! I want to start by acknowledging the mistakes I made when I was left responsible for the other batches and wasn’t as mindful of temperature maintenance in the basement (in colorado) as I should’ve been. That being said, for this batch, I’m bordering on paranoid about the those temps. I brewed a pale ale with an additional oz of flavoring/aroma hops (OG: 1.060) & pitched Safale US-05 dry yeast at 75 F. For the past three days the beer temp has remained virtually fixed between 59-64 degrees - 61-62 is what’s lit up the brightest (I’m using two fermometers to get an averaged reading since they don’t seem very reliable). On the package it says the yeast ferments at a range of 53.6 - 77 F and at an ideal range of 59-71.6 F. So no problem right? That being said, I’ve read a lot of threads on here and some scattered info online that says the US-05 prefers a range of 64-72 - I guess that’s a happy median. Ultimately, I got concerned, so I wrapped my fermenter in blankets to bring it up to that range, but I’m curious: shouldn’t I be fine just leaving it at the range it was at (59-62)? I’m wondering how concerned I should be about this given the indicated temp range on the packet itself. John Palmer says the range provides leeway and peace of mind and the only consideration is preference (sort of - esters, too, at the higher end of the range and longer fermenting times at the lower end... in hoppier beers anyway), but i have no such peace of mind. Thoughts? Tips? Advice? Commiseration?

 

[brewbama]

As you gain experience you will develop a preference for which end of the fermentation range you like.

At this point I recommend you concentrate on how to dry hop and then package your post fermented beer without introducing O2.

 

[Day-Day]

I'm assuming you are measuring temps with the little stick on thermometer on your carboys. Your wort may actually be quite a few degrees higher than that, depending on how vigirous and how far along you are in the fermentation. Some people say that the temp of the wort can be as much as 10 degrees higher than the ambient temp of the room during peak fermenation, as the fermenation gets towards the end, the temp of the wort will drop off.

So if the carboy thermometer says 60-62 and it's peak fermenation, you could very well be closer to 70 degrees. I wouldn't stress, I'd be more concerned about the wort getting to hot, but seems like you've got the temps in a good range.

I ferment my beers in my basement with an ambient temp of 60-62 degrees all the time. I usually use my laundry sink as a swamp cooler during the first 48-72 hours to make sure temps stay down, then I drain the sink and let it ride. In the summer time I'll use the swamp cooler throughout the entire fermentation up until cold crash.

I think you're good man.

 

[ncbrewer]

Some time back, I found instructions for the fermometer on this website:
http://tkachenterprises.com/Products.html The link no longer works, but it includes information about accuracy:
"People have often inquired about the accuracy of the fermometer and what it is measuring when placed on the outside of the fermenter in contact with ambient air. To answer those questions, I conducted an experiment where I put warm water in a glass carboy and placed the entire setup outside in thirty degree weather and compared the fermometer to internal temperatures measured by an immersion fermometer as they came into equilibrium.

What I learned is that for every ten degree difference in temperature between the atmosphere and the fluid in the fermenter, the temperature was off by approximately one degree as follow."

The true internal temperature vs temperature at the wall of the fermenter is a different issue. But I'm confident that during active fermentation, when temperature control is critical, the stirring action of the CO2 bubbles mixes the beer and keeps it all at pretty much the same temperature.

 

[asg816]

I appreciate the advice/info, y’all! My biggest concern was the yeast going dormant just as it should be ramping up, particularly since I’m not familiar with the process of re-pitching yeast yet. I was also worried about the temp varying too much within the ideal temp range, which also sounds like less of an issue than I made it out to be. I figured the readings on the fermometer strips were off, but i wasn’t sure by how much. That being said, it sounds like I’m ok keeping the beer where it’s at in light of what y’all have told me. Also sounds like a bigger concern is the dry hopping and bottling process. Honestly both sounded pretty straight forward, and from my first two times doing it went pretty smooth, but again, noob here so what do I know? I’ve def never heard of bottling without introducing oxygen either, so hopefully I can find that online or in “How to Brew” unless y’all have better sources from personal experience...

 

[Day-Day]

The true internal temperature vs temperature at the wall of the fermenter is a different issue.

This was the issue I was talking about... I'd agree that the mixing that occurs during fermentation mixes the wort and the temp is equalized, but the reading on a fermometer may not be a true indication of the temp of the wort inside the carboy.

 

[Teufelhunde]

I ferment in a mini-fridge with an external controller and set my temp to 62 degrees and don't worry about it, then once the active fermentation dies out, if I need the fridge for a new batch, I set the old batch on the shelf at room temp (72-75) for dry hopping or until I'm ready to bottle......it's been working just fine....

YMMV

Lon

 

[MikeCo]

The beer will certainly ferment at 61-62 with US-05. The flavors you get at the lower range of the recommended temperatures will be different than what you would get at the upper range. I've read many things about peach flavors when US-05 is fermented on the lower end of the range. It will likely ferment much more slowly at 59 than it will at 71.

 

[RM-MN]

So if the carboy thermometer says 60-62 and it's peak fermenation, you could very well be closer to 70 degrees. I wouldn't stress, I'd be more concerned about the wort getting to hot, but seems like you've got the temps in a good range.

Glass is a very poor insulator. What the fermometer reads on the outside of the glass is almost exactly the temperature on the inside of the glass. Even the plastic buckets don't have a very big temperature gradient over the small thickness of the plastic.

 

[MikeCo]

Glass is a very poor insulator. What the fermometer reads on the outside of the glass is almost exactly the temperature on the inside of the glass. Even the plastic buckets don't have a very big temperature gradient over the small thickness of the plastic.

This has been my experience also. The stick-on thermometer is generally close to internal temperatures.

 

[Day-Day]

Glass is a very poor insulator. What the fermometer reads on the outside of the glass is almost exactly the temperature on the inside of the glass. Even the plastic buckets don't have a very big temperature gradient over the small thickness of the plastic.

This is good to know...I've always thought about that, but never took the temp of my wort inside the carboy while fermenting, I just asssumed it was a few degrees higher. Thanks for the info !!!

 

[weaf27]

Like Day-Day said.

So if the carboy thermometer says 60-62 and it's peak fermenation, you could very well be closer to 70 degrees. I wouldn't stress, I'd be more concerned about the wort getting to hot, but seems like you've got the temps in a good range.

It was an eye opener for me when I stopped relying on external temps of my fermentation chamber and started using Tilt Hydrometers (not perfect but great insight) and I was shocked that the temps of a completely sealed and HEAVILY insulated fermentation chamber would still be so different. I can set the chamber (readings are taken from the center axis by a hanging thermometer) to 64 F and my carboys with (pre-calibrated) Tilts will show me temps of 68 F to 72 F based on how active the yeast is. It really helped me to learn that so now I actually place my carboys in my fermentor strategically based on where the locations of my chilling source and heating source are.

I wish I could get low temps easily like you have as it usually helps for a cleaner tasting beer with some yeasts but I work with what I have and use yeasts that prefer my higher temps.

 

[asg816]

Thanks for the suggestions and insight everyone! The two strips I used were helpful in averaging out the temps over the course of fermentation (in my Ale Pale bucket), but I checked it with a sanitized thermometer at dry hop, as well as a few days later and the strips were spot on.

Update: kept it at the low range the entire time - I think one or two days it even dipped to 58-59 before returning to 60-62 - and the fermentation was as close to ideal as I could hope for or expect. Didn't know about diacytl rest at the time, so that never happened. Bottles are approaching two weeks conditioning at 70 degrees and if they're anything like the one I taste tested at one week to familiarize myself with the process, these beers are gonna be pretty damn good (peach flavors for sure @MikeCo, as well as an abundance of tropical fruits and citrus, notable hop forward flavor with a nice, lingering finish - which I'll adjust in my second batch [i.e. no more Apollo hops for bittering, I'll throw in some mosaic to match the flavor profile] and a clean malt backbone). Interesting that the final IBU's and gravity measurements have this at the extreme end of the pale ale spectrum somehow and right, smack dab within range of an IPA - West Coast in this case. Either way, stoked with the results so far and excited to tweak the recipe next weekend!