When do you consider your fermentation to be stuck?

Discussion in 'General Brewing Discussions' started by Bumpy Bear Brewery, Mar 1, 2020.

  1. Bumpy Bear Brewery

    Bumpy Bear Brewery New Member

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    So, I've not had this problem myself yet but preparation is key in my eyes and I'm interested it what others think.

    When it comes to fermentation when does everyone consider it to be stuck. For example, if you are aiming for an FG of say 1.010 but fermentation stops short would you consider it to be stuck if it was 0.002, 0.005, 0.010 too high?

    Thoughts?
     
  2. Megary

    Megary Well-Known Member

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    #2 Megary, Mar 1, 2020
    Last edited: Mar 1, 2020
    Lots of ways to answer this and you will get better answers than mine.

    I don't necessarily consider a stuck fermentation based on numbers but rather what I observed while ferm was taking place. Was the pitch done correctly with healthy yeast? Was the temp controlled properly? Did Krausen look normal? Was there typical air-lock activity? (I know, but still every observation helps)

    And that's not to mention how fermentable the wort was to begin with. Mash temp, pH, recipe etc. all play a part. Fwiw, I find I get less attenuation in darker/roastier beers than I do in lighter styles. That could be the wort or it could be that I'm not controlling pH as well with the dark grains. (I'm currently working on a theory!)

    Sometimes it's not a stuck fermentation, sometimes expecting an average attenuation from the yeast can be a little unreasonable in the first place.

    I'm not sure I really answered your question but rather just asked it again!

    Anyway, if you're off by .010, something didn't go according to plan.


    **edit for not proofing before submitting**
     
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  3. Nosybear

    Nosybear Well-Known Member

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    Best answer is when there's no change in gravity over 3 days. You can use either a hydrometer or refractometer to make this determination.
     
  4. Bumpy Bear Brewery

    Bumpy Bear Brewery New Member

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    Completely agree with what you are saying but should my FG be off by 0.010 in a big beer, say OG of 1.095, I would consider that acceptable compared to the same situation in a smaller beer with an OG of 1.045.

    I'd be interested to know of anyone works by a hard and fast rule when it comes to under attenuated beer as we all know it's more of an art than a science.
     
  5. Nosybear

    Nosybear Well-Known Member

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    There is no rule. Trust your instruments.
     
  6. BOB357

    BOB357 Well-Known Member

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    If you're pitching an adequate population of healthy yeast into a well aerated/oxygenated wort, you'll seldom have a problem with stalled fermentation unless the alcohol level exceeds the tolerance of the yeast strain. There are exceptions, but they're few and far between if you've done some research and determined if the strain has any particular idiosyncrasies that you need to account for. There are, of course, problems with inaccurate entries to brewing software or other errors in the calculations, as well as anything that produces a wort that's considerably less fermentable than planned.
     
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  7. Mark Farrall

    Mark Farrall Well-Known Member

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    I'd be more inclined to talk about the percentage attenuation difference, rather than specific gravity or plato. So something like your yeast is expected to give 75% attenuation but you've got 60%.

    That then lets you push the conversation back to the points Megary mentioned, where you try to work out what happened and whether that average attenuation was realistic for this batch. I recently moved to a DIY electric BIAB system. First few mashes were a disaster, mash temp was massively high. I hit the numbers, but fermentability was awful. I only got a 55% attenuation instead of an average 75%. So it wasn't a 'stuck' fermentation, just a terrible mash.

    So once you've got a working explanation, you can then go to the next step. What am I prepared to do about it? Those options will change based on what the problem was. For me, with a poor mash, the options I thought of were adding enzymes to the fermenter, add a diastaticus yeast or add brett. There's probably others. And there's the other option that often gets missed when you go down this rabbit hole, do nothing.

    First beer was a low ABV kettle sour. I carbed up a small sample and it was fine. So I just let it finish high. Dragged it out to a friends party a few weeks ago and everyone actually loved it. So I'm thinking I may change to a lower attenuating yeast for future batches. My mate's mother (in her 70s) wine drinker her whole life, didn't drink anything else.

    Second beer was dark and big and the sample was ok, but a bit disappointing compared to previous batches. I added WLP099, a diastaticus yeast, that started breaking down the unconverted starches from the bad mash. It ended up finishing lower than the recipe predicted and it's still just an OK beer that's not as good as previous batches. It'll probably get dumped the next time I need a spot in the kegerator.
     
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  8. J A

    J A Well-Known Member

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    I've got a couple of lagers right now that are being stubborn. They're both just on the cusp in terms of being problematic, though I don't consider either "stuck". I'm expecting .008 or .009 and one is hanging tight at 1.011 and the other finally budged down from 1.013 after a few days at 67. Big pitch, fresh slurry but I was out of O2 and couldn't add oxygen like I usually do.
    Plenty of beers are okay if they're as much as 4 or 5 points high but low OG beers really lose a lot of appeal when they're too sweet.
     
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  9. Trialben

    Trialben Well-Known Member

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    Often when I see brewer posting on the forums it's a stuck fermentation at the dreaded 1.020!
    I've been there myself on a barley wine that I got to budge with some slurry from a freshly fermented second running batch.

    Another tool is the FFT :rolleyes: Fast Ferment Test where you take a portion of wort And ferment this or like I've been doing spin it up on the stir plate as a yeast starter for next batch.
    You can use the starter FG as an indicator to guage how your primary fermentation is going.
     
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  10. Yalc

    Yalc Member

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    I do this with every brew. If they’re close with a few points no problem. If upwards of 10 points I know it is a ferm issue not wort related.
     
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  11. ^Tony^

    ^Tony^ Active Member

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    I know this is an old thread but: I recently ran into my first stuck fermentation (at least I think it is stuck) I made a cream ale recipe that I have made several times before, with S-05 like I have used for tons batches. OG: 1.062 (I missed to the high side) Usually the FG: 1.012-1.010. After 5 days it got to 1.022 and stopped dead. After another 6 days, raising the temp to 21c, agitating the fermenter, re-pitching another pack of S-05 aaaaaand nothing. The only difference is I ended up with a whole bunch of kettle trub in the fermenter..which may have done it but I doubt it. And I realized I forgot to oxygenate (usually I do it while transferring to the fermenter then shake the bajeebers out of the fermenter.) I don't want to add O2 now so I will take it as is at 1.022 and call it lesson learned. And at 5.25% ABV it will give you a nice glow after a few. I thought it would be way too sweet but turns out it is one of the most true to style (taste wise) cream ales I have ever made. Go figure....:rolleyes:

    I shoot for the FG calculated by the recipe builder but I don't worry too much if I don't hit it. If I am close-ish, as long as the ferment is done, I don't get bottle bombs and it's not too sweet, I'm okay with it.

    A higher than expected FG does not necessarily mean bad beer. Sometimes it's just a number that tells you to start sampling.
     
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  12. Hawkbox

    Hawkbox Well-Known Member

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    That's a bit high but you may have just mashed high too. I wouldn't worry about it though.

    I do almost nothing to filter what goes into the brew bucket and I only oxygenate during the transferring of liquid so I doubt you have any serious issues there.
     
  13. ^Tony^

    ^Tony^ Active Member

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    Yeaaaaah. I'm still trying to dial in the process for my new kettle....it's a process
     
  14. Hawkbox

    Hawkbox Well-Known Member

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    I'm incapable of leaving things alone and doing something the same way twice so I am still dialing things in.
     
  15. ^Tony^

    ^Tony^ Active Member

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    :DI find I am that way with my recipes...I seem to be completely incapable of keeping them exactly the same brew to brew, even if I find one I love.
     
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  16. Hawkbox

    Hawkbox Well-Known Member

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    There are a couple I did early on that I really wish I had left alone cause I don't remember how to recreate them now.
     
  17. Craigerrr

    Craigerrr Well-Known Member

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    We are homebrewers, we are not robots, say it with me now...
     
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  18. AGbrewer

    AGbrewer Active Member

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    Expected yeast attenuation along with a stable FG for 5 days is what I typically look for.

    I've got one right now that started at 1.152 and is stuck at 1.056

    Attenuation is at 61%, but I expected the main yeast to stop as the ABV is above 13%

    So I pitched a 1 liter high krausen starter of WLP-099 which is good to 25% ABV, however I haven't seen any movement in over 10 days since I pitched. Normally I pitch the wlp-099 3 days after the main yeast, but tried something different this time. Not sure why it didn't kick in, but it's definitely stuck now. I've tried swirling, but no luck.

    Probably going to try a wine yeast to see if that will work.
     
  19. Trialben

    Trialben Well-Known Member

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    Ferm temp is nice and warm? That's all I've got seems you've tried everything else
     
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  20. AGbrewer

    AGbrewer Active Member

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