Slow fermentation?

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aaronmq

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I have a bit of a head scratcher. At the end of August, I brewed a Brown Ale (OG 1.050) that was supposed to ferment to 1.011, but it stalled at 1.030. I fermented at 68F with Lallemand London English Ale. I attributed the stall to one or both of the dumb mistakes I made when brewing:

First, I forgot to turn off the heating element when I mashed in (152F mash temp) and it got to strike temp (162F) before I was able to get the temp back down... took about 10-15 min. to get back down to 152F. Boneheaded mistake, but I didn't expect it to have a major impact.

Second, I spund my beers. So after a couple days, I opened the ferm chamber to check gravity using a tilt (I need to get right next to the fermenter to get a reading). It was at 1.030, so I didn't apply the spunding valve at that point, but in the process, I must have knocked the temp probe off the side of the fermenter and it hung outside the chamber when I closed it. I use a mini-fridge as a chamber, so with the probe at ambient, I essentially cold-crashed my beer at 1.030. After another day or two, I realized what happened and my beer was at 35F. RDWHAHB, right? So I let it get back to fermentation temp however, it never moved off of 1.030. I raised the temp to 75F and still nothing.

I gave the fermenter a shake (I use 6.1 gallon torpedo kegs to ferment, so no concerns of introducing O2) to rouse the yeast... Nothing.

I took a sample to check the gravity using a hydrometer in the event the tilt was malfunctioning.. It too read 1.030.

In a last ditch effort to solve it, I used the beer to make a starter and added it back to the beer. Nothing.

At that point, I assumed the beer had reached a high FG due to the high initial mash temp. I had no interest in drinking the beer at 1.030, so I intended to dump it as a sacrifice to the beer gods for my mistakes, but set it aside in the mean time.

A week ago when checking the gravity of another beer, my tilt app got a read on the Brown Ale and it read 1.029. I didn't think anything of it as it can fluctuate slightly, but figured I'd keep an eye on it. A few days later, it read 1.027. I checked again today... 1.023.

I don't know if it was already "stalled" at 1.030 when I accidently cold crashed it or if it was actively fermenting, causing it to stall at 1.030.

Regardless, I'm confused now. Could the high mash temp have made some of the sugar more difficult to ferment resulting in the slow drop from 1.030 to 1.023?
Could I have picked up an infection when adding back the starter I made and bacteria is able to ferment what the yeast couldn't?
 
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hotbeer

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Could I have picked up an infection when adding back the starter I made and bacteria is able to ferment what the yeast couldn't?
Could be something wild got in. Could be other things. Infection doesn't necessarily mean dump if you like what the results taste like.

Has the beer ever gone clear and then clouded up again? Or has it remained cloudy in the FV?

I wouldn't have used O2 to rouse the yeast after the initial krauesen. I don't even think O2 rouses yeast. It's more something they use when they go through certain early phases and need to produce sterols for reproduction or such. So if you were to overpitch your yeast which most do, there isn't much seeming need for the reproduction part. But I'm not really knowledgeable on the yeast biological stuff. So read up or look for the response of others on this.

I'd think the O2 after the initial krauesen would give you a stale cardboard taste.

I have had beers go six weeks in the FV. I wasn't checking SG in them during that time, so I can't say what that was. However they'd seem to clear up, then get cloudy and bubble again with very tiny fine bubbles in the beer itself, then clear up and later go cloudy again. They were still a very great tasting beer to me. But still, I'm worried about that O2 you added after the krauesen. As well as any other dinking around with it you may have done.
 
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aaronmq

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You used the stalled beer to make it? No added sugar/DME/etc? New yeast? Sounds like it didn't do much for the full batch, but how did it act in the starter itself?

I used DME as the starter wort, and added some of the stalled beer to step up the suspended yeast. The starter had no problems and made short work of the fresh wort. I was already suspecting that the initial high mash temp resulted in less fermentables, but I figured some more yeast cells in the batch may help. At that point, I assumed if more cells didn't move the needle off 1.030. then it was at FG.
 
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aaronmq

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Has the beer ever gone clear and then clouded up again? Or has it remained cloudy in the FV?
I couldn't tell you, I ferment in a 6 gallon keg.

I wouldn't have used O2 to rouse the yeast after the initial krauesen. I don't even think O2 rouses yeast.

No, I meant I didn't need to worry about O2 because I ferment in a keg. I knew I wouldn't introduce O2 by shaking the FV like I would if I was using plastic buckets.
 

hotbeer

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I gave the fermenter a shake (I use 6.1 gallon torpedo kegs to ferment, so no concerns of introducing O2) to rouse the yeast... Nothing.

No, I meant I didn't need to worry about O2 because I ferment in a keg. I knew I wouldn't introduce O2 by shaking the FV like I would if I was using plastic buckets.
Oh!

I can see that now.
 
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aaronmq

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Down to 1.022 this morning. I fully intend on letting this go as far as it possibly can in hopes of hitting the target FG, but does anyone have any clue what is going on?

It sat at approx. 70F for almost 3 weeks after adding more yeast before gravity started to drop slowly (a little less than a point per day).

I checked the Tilt logs and here is the timeline:

30AUG - Brew day: OG 1.050 set chamber to 68F
2SEP - Checked gravity w/ Tilt: 1.030... accidently dropped chamber to 34F
4SEP - Checked gravity w/ Tilt: 1.030... realized chamber was cold, returned chamber to 68
8SEP - Checked gravity w/ Tilt: 1.030... Increased chamber to 75F
10SEP - Checked gravity w/ hydrometer: 1.030. Made a starter using the yeast in suspension of "stalled" beer
11SEP - Checked gravity w/ Tilt: 1.030... added yeast starter
13SEP - Checked gravity w/ Tilt: 1.030... removed from chamber and set aside in 72F room.
29SEP - Checked gravity w/ Tilt: 1.030.
2OCT - Checked gravity w/ Tilt: 1.030.
3OCT - Checked gravity w/ Tilt: 1.029.
4-6OCT - Checked gravity w/ Tilt: 1.028.
7-8OCT - Checked gravity w/ Tilt: 1.027.
9-10CT - Checked gravity w/ Tilt: 1.026.
12OCT - Checked gravity w/ Tilt: 1.023.
13OCT - Checked gravity w/ Tilt: 1.022.

Thoughts?
 

hotbeer

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Yeast got mad at you for dropping the temps so low then warming it up so quick. Probably PO'd them and they wanted to make you sweat!

The OG was with the tilt? If different device, did you compare to double check the Tilts calibration?

Just because it's sugar water doesn't mean it's all fermentable by the yeast you used. So the temperature excursion during your mash is also still in play. But the temps you reported seem not too bad compared to things I've done wrong. Assuming you caught the highest temp any part of the mash may have gotten too.
 
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aaronmq

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Yeast got mad at you for dropping the temps so low then warming it up so quick. Probably PO'd them and they wanted to make you sweat!

At this point, this seems like the only possible explanation. I have never seen such a long delay during fermentatio.

The OG was with the tilt? If different device, did you compare to double check the Tilts calibration?

Just because it's sugar water doesn't mean it's all fermentable by the yeast you used. So the temperature excursion during your mash is also still in play. But the temps you reported seem not too bad compared to things I've done wrong. Assuming you caught the highest temp any part of the mash may have gotten too.


The OG was with a hydrometer and validated with the tilt.

Yeah, when it stayed at 1.030 after raising the temp and adding more yeast, I was convinced many of the sugars were not fermentable because I messed up the mash at first. I pulled it out of the chamber to dump it, but I was too lazy to do it at that point. My procrastination may have paid off because something is certainly happening right now.
 

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