Stuck fermentation

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welly2

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My oatmeal stout has decided to stop fermenting any further. OG was 1.055 and is currently sitting at 1.020 and not shifting. I pitched S-04 yeast into it. From what I've read, this isn't a rare thing and S-04 seems to have a habit of doing so. Is there anything other than pitching another pack of yeast into it to get it going again?

I did give it a good shake before I pitched the yeast and I always stick a bit of yeast nutrient into it.
 

welly2

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Ok, further research shows giving it a bit of a swirl and raising the temperature a bit (it's currently at 17.5c) might give it a new lease of life. So I'll try that. I'm not expecting it to drop much below 1.020 but I'd have thought it should get down to at least 1.015.
 

Dan Pratt

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Raise the temp to 21c. The flavours have already been created from the main ferment, increasing to 21 will wake them up and it will ferment out, provided your mash temp was correct, if you happened to mash at 70c it wont get much lower.
 

welly2

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Pratty1 said:
Raise the temp to 21c. The flavours have already been created from the main ferment, increasing to 21 will wake them up and it will ferment out, provided your mash temp was correct, if you happened to mash at 70c it wont get much lower.
Mashed at 66c so should be good for a bit more fermentation! Anyway, we'll see what happens. I've set the STC to up the temperature a bit more and given it a bit of stir.
 

MHB

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Have you thought about why?
Once a ferment starts it really is pretty hard to stop it before it completes. Especially in my experience with S-04 it is one of the most reliable dry yeasts on the market.
Yeast pitched into a healthy well aerated wort should reproduce to a population 6-8 times the original pitch, so adding another packet is not really all that helpful.
I would be taking a long hard look at how stable my temperature control was, how well aerated the wort is, the fermentability of the wort...

Its a bit harsh blaming the yeast, if the brew started fermenting, generally a stalled ferment is down to the brewer, would be good for your future brewing to work out why.

Mark
 

louistoo

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I had this problem with S04 and tried a raise in temp and swirl, it did go down a bit more but not to expected final gravity. I then had US05 do the same thing on brews I was mashing for medium body at what I thought was about 67c, they stopped well short of expected fg.. around1.020!
The penny dropped after a deal of swearing and annoyance and upon testing my spirit thermometer discovered I'd actually been mashing at 70. Now I have a thermopen which while being costly came with a certificate guaranteeing accuracy, you could try mashing at a lower temp with your current thermometer but it's nice to be confident about temp.
 

MHB

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Sort of my point, you didn't have a problem with the yeast (either of them) you had a mashing problem, you found the problem and fixed it - best answer possible.
Mark
 

Bribie G

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If you mashed at 70 then a FG of up to 1022 would be quite normal.

I used to do mild ales for competitions and just used the same grain bill as doing a "full strength" brew of say 1048 but never let the mash go below 70 and ended up with sub 4% beer after a FG of around 1020

I had to take those measurements accurately because in that particular comp I had to declare OG and FG on the entry form.

You don't have to spend a fortune on thermometers, I just use a couple of $15 Robins Kitchen or Target stick thermometers, calibrate them with ice and boiling water, check that they are both within half a degree of each other and use the best one. Hit my gravities no problems.
 

welly2

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MHB said:
Have you thought about why?
Once a ferment starts it really is pretty hard to stop it before it completes. Especially in my experience with S-04 it is one of the most reliable dry yeasts on the market.
Yeast pitched into a healthy well aerated wort should reproduce to a population 6-8 times the original pitch, so adding another packet is not really all that helpful.
I would be taking a long hard look at how stable my temperature control was, how well aerated the wort is, the fermentability of the wort...

Its a bit harsh blaming the yeast, if the brew started fermenting, generally a stalled ferment is down to the brewer, would be good for your future brewing to work out why.

Mark
Well, that's a fair comment but my brewing routine is pretty consistent these days and this has never occurred before. The only single thing that changed with this particular brew was I no-chill cubed it rather than using my chiller. My fermentation fridge hasn't changed, I aerated the wort as I normally do, I rehydrated the yeast as I normally do. Nothing has changed other than the yeast. With the exception of using WLP007 in a brew a month ago, I've been using US-05 consistently this year and never had a stuck fermentation this year. And actually this is literally the first stuck fermentation since I've started brewing. So I guess something must have changed in my process but nothing I could point a finger at. Anyway, will see what happens now I've upped the temperature a bit and given it a stir. If it doesn't drop, it doesn't drop. It won't be the end of the world and I'll still have beer!
 

MHB

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No doubt, but if the yeast has peeled off 35 points (63% apparent) there is going to be a dam good reason why it has "stalled".
It is really up to you whether or not your happy with the outcome, a bit of basic investigation might point up where the problem is and that should help you make better beer.
At a bare minimum make sure your mashing and fermentation temperatures are what you think they are (a good glass lab thermometer is less than $20 and a very worthwhile investment). Its worth measuring the temperature in your fermenting fridge at the top and bottom there can easily be a 5oC difference (putting a small fan in the fridge makes sense) the bottom can be cold enough to stop the yeast while you think the fridge is warm enough - depending on your sensor location.

Just good basic brewing process and practice - frankly S-04 is the most reliable dried yeast I have ever used - generally a lot more reliable than the brewers who try to blame it for its performance. (well T-58 would give it a run...)
Mark
 

wessmith

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And I would implement a good old fashioned Iodine starch test - how do you know all the oatmeal converted?

Wes
 

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welly2 said:
Well, that's a fair comment but my brewing routine is pretty consistent these days and this has never occurred before. The only single thing that changed with this particular brew was I no-chill cubed it rather than using my chiller. My fermentation fridge hasn't changed, I aerated the wort as I normally do, I rehydrated the yeast as I normally do. Nothing has changed other than the yeast. With the exception of using WLP007 in a brew a month ago, I've been using US-05 consistently this year and never had a stuck fermentation this year. And actually this is literally the first stuck fermentation since I've started brewing. So I guess something must have changed in my process but nothing I could point a finger at. Anyway, will see what happens now I've upped the temperature a bit and given it a stir. If it doesn't drop, it doesn't drop. It won't be the end of the world and I'll still have beer!
I had the same and it turned out that my thermometer (good one brew then 6C out the next) was the problem. I simply tested it against two others to find this out. It was adjustable so I corrected it, but it has never been trusted again. Same as you, my processes didn't change, but the outcome was quite different (my issue wasn't a stuck fermenter, rather a low efficiency, but you get the point).
 

welly2

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wessmith said:
And I would implement a good old fashioned Iodine starch test - how do you know all the oatmeal converted?

Wes
True. I did just recently buy a bottle of iodine and did an iodine test on the pale ale I brewed the other day - that all converted so should be good. Like I say, it's never happened before and I can't think of anything that I did differently. I checked the gravity this morning and it's dropped a point or so, and so looks like fermentation is kicking off again after giving in a stir and bumping the temperature up.
 

welly2

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Jack of all biers said:
I had the same and it turned out that my thermometer (good one brew then 6C out the next) was the problem. I simply tested it against two others to find this out. It was adjustable so I corrected it, but it has never been trusted again. Same as you, my processes didn't change, but the outcome was quite different (my issue wasn't a stuck fermenter, rather a low efficiency, but you get the point).
I've got a thermapen which should be pretty accurate and I've got a thermometer that I use in my other hobby of developing/printing black and white photographs so I might test the pair of them against each other and check the accuracy, and also check the accuracy of my grainfather. Might be half an hour well spent.
 

jayjt29

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Id say the FG might be the lowest it will get, some of my more heavy beers have finished well above 1.010 and tasted spot on :)

Jay
 

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welly2 said:
Well, that's a fair comment but my brewing routine is pretty consistent these days and this has never occurred before. The only single thing that changed with this particular brew was I no-chill cubed it rather than using my chiller. My fermentation fridge hasn't changed, I aerated the wort as I normally do, I rehydrated the yeast as I normally do. Nothing has changed other than the yeast. With the exception of using WLP007 in a brew a month ago, I've been using US-05 consistently this year and never had a stuck fermentation this year. And actually this is literally the first stuck fermentation since I've started brewing. So I guess something must have changed in my process but nothing I could point a finger at. Anyway, will see what happens now I've upped the temperature a bit and given it a stir. If it doesn't drop, it doesn't drop. It won't be the end of the world and I'll still have beer!
Hi Welly,
Have you brewed this current recipe with your current process and that yeast before?

When you say nothing has changed, is this a new recipe, or something you knock out frequently with SO04? So you have a known Final Gravity that you expect? If so what is that?

Cheers Steve
 

stewy

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welly2 said:
My oatmeal stout has decided to stop fermenting any further. OG was 1.055 and is currently sitting at 1.020 and not shifting. I pitched S-04 yeast into it. From what I've read, this isn't a rare thing and S-04 seems to have a habit of doing so. Is there anything other than pitching another pack of yeast into it to get it going again?

I did give it a good shake before I pitched the yeast and I always stick a bit of yeast nutrient into it.
//

S04 can be a bit fussy but a great yeast when handled well. I tend to pitch (rehydrated) at 17C, leave it for 48-72 hours then raise 1C per day until I hit 21C.... Tends to allow it to attenuate fully. A gently swirl a couple of times a day doesn't hurt also.

Given you are past that, I would sanitize a large spoon & stir the yeast up from the bottom & set temp at 21C... That should knock off any remaining points
 

welly2

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Brewman_ said:
Hi Welly,
Have you brewed this current recipe with your current process and that yeast before?

When you say nothing has changed, is this a new recipe, or something you knock out frequently with SO04? So you have a known Final Gravity that you expect? If so what is that?

Cheers Steve
New recipe and new yeast. So I guess it's anyones guess but I checked it today and it's not shifted. I think it's done! Time to bottle her up.
 

louistoo

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Where did you buy potassium iodine Welly?
 

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