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Fermentation temp

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html034

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I am sorry if i am repeating a thread that has been done before, but I have been searching, and have been unable to find an exact answer to my question. When I read a number referring to a temperature for optimal fermentation, does this number refer to the ambient air temperature around the fermenter, or the actual temp within the fermenter, which is higher due to yeast activity.

I ask this because i brewed a batch on Friday that I think may have been too hot. I brewed it on Friday and within 8 hours bubbles started coming through the airlock constantly all day Saturday, to the point where water from the 3 piece airlock began to come through the tiny holes in the top of the airlock. The stick on thermometer on the side of the bucket read the highest mark, 78 degrees for most of the day, but my house's thermostat was only set to 67-68 degrees. I thought that it would be okay because i read that the temp in the fermenter could be up to 10 degrees higher than the air temp, but now I have read things that make me unsure. can someone please straighten this issue out for me once and for all? Is my Brown ale going to turn out a fusel alcohol riddled mess? :confused:

Thanks in advance for the help. I really like this website because there is so many people that are willing to help. I can imagine that it must be annoying to the veteran brewers to field the same beginner questions over and over again, so i really appreciate the way that even the stupidest questions get answered promptly again and again. Just thought i would express my appreciation.:)
 

Evan!

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The temp in the carboy (stick on thermo) is what you should be concerned about. As you've noticed, aerobic activity during fermentation can raise the wort temp 10 degrees or more above ambient temps.

So when a yeast's optimal fermentation temp is 68f, and your stick on thermo reads 78f, you've got a problem. There's no way to tell right now whether it'll be a "fusel alcohol riddled mess", but I will say this: few things are as important to the quality of your finished beer as keeping your fermentation temps under control. For most ales, this means below 70f.
 

s3n8

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I brewed an extract imperial stout kit 8 days ago. It has been happily fermenting for 7 of those days at the bottom end of the recommended temp range (65 F). It appears to be slowing down, and now has about 2cm of krausen left on top. I am hoping for a nice clean and complete ferment. My first kit I obsessed about the temp and moved it to a warmer area of my basement for a couple days (blew krausen and yeast out of the airlock and made a small mess) then to a slightly cooler part, then back to warmer, and cooler...

All of my obsessing and moving around didnt do anything good to my beer, and it finished a little high. 1.02 for an IIPA. Not a lot high but a little, and I can taste some residual sweetness which I hope to age out. I am taking the exact opposite approach to this one, keeping cool, dark, and un-f'd around with. Hoping for improved results. Gonna be a while before I know though, directions say ~6mos to age out. I have read several places that say to shoot for the low end of the suggested range and let things progress slowly.
 

riored4v

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How quick can the fusel tastes occur?

I brewed my IPA on Saturday and fermentation took off quick vigorous. TONS of airlock activity, etc. When things got going, the temps went up to around 72-73. I tried getting the temps down with a fan, but that didn't seem to work.

Yesterday I tried the wet-towel trick and I got my temps down to about 67-68. So basically I was at 72-73 for the first 2 days, and from here on out, it should be at a cooler temp.
 

riored4v

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anyone?

i'm not really worried about it, but i was just curious about the timeframe in which the offtastes could occur.

activity seems to have slowed on mine and is staying steady at around 67.
 

s3n8

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I dont know about the fusel alcohol you are worried about, but chill out, im sure its fine. Go get yourself a few good brews and let the ferment complete. No sense obsessing about it because there isn't much you can do but wait and see, and make adjustments to your process accordingly for the next batch.
 

riored4v

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s3n8 said:
I dont know about the fusel alcohol you are worried about, but chill out, im sure its fine. Go get yourself a few good brews and let the ferment complete. No sense obsessing about it because there isn't much you can do but wait and see, and make adjustments to your process accordingly for the next batch.
obviously you didn't read my post

i'm not really worried about it,
no where did i say i was stressing, obsessing or even concerned as my beer is doing it's thing and i'm being plenty patient about it and i feel it'll still be perfectly fine.

I'm here trying to learn a few things, thus the reason for asking the question.
 

Judd

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Great question, html034. I don't really have anything to add, except thanks for doing your research and giving lots of details in your questions. Newbies like you are always welcome and appreciated.
 

hagen505

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I always like the questions that are considered newbie questions. Those are the ones I most often check out. Alot of them, such as this one, are questions I never really think to ask, but are great for info.

p.s. I'm not saying anyone was giving him a hard time.
 

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