When do you consider fermentation to be complete

Discussion in 'Beginners Brewing Forum' started by Coronajax, Jun 18, 2020.

  1. Coronajax

    Coronajax Member

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    As the intro suggests I'm looking for input regarding when you consider fermentation to be complete. For example, I just brewed a blonde ale on Saturday, pitched the yeast (dry) Saturday afternoon and by midnight it was starting to bubble in the airlock. Sunday and Monday had pretty vigorous action but as of today, it's tapered off a lot. At what point is it done? No activity at all? I'm just concerned about letting it sit too long if the activity in the airlock is minimal.
     
  2. Sunfire96

    Sunfire96 Well-Known Member

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    Do you have a hydrometer or refractometer? Unfortunately, measuring final gravity 2-3 days in a row and getting consistent results is the only way to know for sure. I do small batches and don't want to lose final volume to multiple tests, and I've had issues with bottling before fermentation was actually complete. From now on I'm going to wait at least 2 weeks before checking FG, if not 3 weeks. Best of luck with the batch! Cheers!
     
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  3. BrewPatgonia

    BrewPatgonia Well-Known Member

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    I usually wait until the airlock is bubbling less often than 1 time in 60 seconds.... I also check the specific gravity... verify that it is close to the expected terminal gravity and also that it doesn't change in three days or longer.... ex. if sg is 1.018 today, and thee days later still at 1.018 ; then fermentation is complete... even if my expected was 1.015 ; I would still wait another 7 to 10 days to allow time for the yeast to clean up their 'mess'.

    You almost can't wait too long... you can let the yeast sit (without causing harm) for 3 to 5 weeks after activity stops. *I would be nervous to let it go much past 6 weeks from halting of activity in the airlock.
     
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  4. Herm_brews

    Herm_brews Well-Known Member

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    I brew small batches, a gallon and a half at a time. My approach is simple, and I am patient. Three weeks in primary, then if and when I am ready, I bottle. I lose none of my finished brew to analytical sampling, which means that I don’t know my final gravity, or abv, or attenuation. The beer seems good to me, so I brew more, and drink it. Continue.
     
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  5. okoncentrerad

    okoncentrerad Active Member

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    I have two approaches,

    either I use my TILT to get a hint if it's reached the estimated FG, then I wait a few extra days and take a hydrometer reading. If it's where it's expected to be I call it finished.

    The other approach if I don't use the TILT is to just wait a week or perhaps a few extra days, then check FG. It's almost always where it's supposed to be but I wait a day or two to check once more and bottle/keg.

    Usually I keg/bottle by day 10, or so, but I have done a few days earlier and a few days later, but then usually because I didn't have the time to do it earlier.
     
  6. Bubba Wade

    Bubba Wade Well-Known Member

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    Keep in mind that after obvious activity has diminished (bubbling through the airlock), the yeast are still active. Depending on the nature of the beer and yeast, there are still activities going on with the yeast continuing to metabolize fermentation byproducts even though very little CO2 may be produced during this period. For most beers this lasts a week or two. I usually leave my batches in the fermenter for a week or so after I hit final gravity.

    After this, I carbonate naturally in the keg and allow another two weeks or so of aging.

    Everyone has a bit different process based on their equipment, setup, and patience level.
     
  7. Coronajax

    Coronajax Member

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    Thanks for the responses, I think I'll wait until the weekend at least, maybe even next week before I do anything. Interesting to see some of the different methods used.
     
  8. BOB357

    BOB357 Well-Known Member

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    It's fairly common for active fermentation to finish in just a few days with an adequate amount of healthy yeast and plenty of oxygen in the wort. This doesn't necessarily mean that the yeasts have finished their work and the beer is ready to package. Many beer styles will improve greatly with extended time in the fermenter, while some are best packaged, conditioned and served as quickly as possible.

    If you're just wanting to know when your beer is safe to bottle, once the Krausen has receded, check the SG. It should be very close to the expected FG. Do a second check after at least 48, preferably 72 hours. If the results are the same, you're safe to bottle. Small batch brewers often just rely on extended time in the fermenter rather than wasting the beer it tales for 2 gravity tests. Not quite as reliable as gravity checks, but usually works just fine.
     
  9. BarbarianBrewer

    BarbarianBrewer Well-Known Member

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    For the longest time that was my rule as well. I don't remember which forum it was on but there was a good discussion on how long beer can sit in primary before off flavors begin to be detected. A number of brewers said they have left beer in primary for 2-3 months (or more?) without any issues. I still don't let it go over 4 weeks in primary but, if I ever do need to leave it sit for longer, I won't worry.....at least not as much! ;)
     
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  10. Hawkbox

    Hawkbox Well-Known Member

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    I largely consider it done when I get bored and want the fermenter back to make more beer. Kegging makes things a lot more forgiving though.
     
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  11. BOB357

    BOB357 Well-Known Member

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    There is that. When I bottled, many moons ago, I always did 2 weeks in primary and 2 weeks in secondary. I did do a gravity check before bottling, but nobody was touting a second check for stability. If the gravity was within a couple points of expectation, it was ready to bottle. Never had a gusher or bottling bomb.
     
  12. Coronajax

    Coronajax Member

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    Update, after a few days of inactivity in the airlock I decided to do a FG check to see where I was at. The recipe suggested 1.009 to 1.011, I would say I'm pretty much spot on so I'm going to cold crash today.
    WP_20200621_001.jpg
     
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  13. Hawkbox

    Hawkbox Well-Known Member

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    Looks pretty bang on.
     
  14. rwinzing

    rwinzing New Member

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    I think three days at a number is normally when I think it is done. It does some clean up later as well. You don't want to rush it. I have had many beers finish below the "target" number. Patience is key. For a medium gravity beer it is a min two weeks in the fermenter before I move it.
     
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  15. AHarper

    AHarper Well-Known Member

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    My latest brew has a "calculated" OG of 1.072, and a Final SG of 1.010. This is for 18lt (4 Gallons) in the fermentor, one packet of yeast with attenuation of 80% set in the recipe. Fermentation done in an Inkbird temperature controlled fridge set to published temperatures.

    So far the brew has reached a SG of 1.002 and it has slowed down - 3 readings in last 24 hours the same - so I have a few questions.

    1. Do you try and stop fermentation at the suggested FG?
    2. Do you just let the fermentation progress to completion naturally - let the yeast do its thing?
    3. Is the yeast used far better than the published/expected attenuation?
    4. Should I bother about what the recipe builder predicts and just use it as a "guideline" (as they say in Pirates of the Caribbean)?
    5. Am I worrying (too strong a word) unnecessarily?
     
  16. BOB357

    BOB357 Well-Known Member

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    What are you brewing? If your SG of 1.002 is accurate, I'd assume it's something other than beer unless you added enzymes.
    As a rule, stable gravity for 3 days means that fermentation is complete, but I question the accuracy of the FG reading if it's beer you're brewing and you haven't added enzymes.
     
  17. AHarper

    AHarper Well-Known Member

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    Hi Bob,
    Im brewing a Belgian Dubble: https://www.brewersfriend.com/homebrew/recipe/view/1015466/foredown-lockdown
    No enzymes added unless you mean Dextrose?
    The readings are from a Tilt.
     
  18. BarbarianBrewer

    BarbarianBrewer Well-Known Member

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    1 & 2: While you can help yeast along by giving them the right environment, always let the yeast do their thing on their schedule. As Denny Conn says, "Yeast want to make beer".
    3: I don't know. I've never compared actual vs predicted attenuation.
    4: Correct, it is just a guideline. (Love that movie)
    5: Probably...but that's part of the fun of the hobby...as long as you don't obsess over it.

    As Bob said, readings should be stable over 3 days. But others just ferment 3-4 weeks and assume it's done if the FG is close to expected. But, 1.002 is concerning. Did you correct for temperature? Use the Hydrometer Calculator for that. If that is a true reading then I would worry about an infection.
     
  19. Megary

    Megary Well-Known Member

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  20. BOB357

    BOB357 Well-Known Member

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    That helps a lot. The low mash temperature, simple sugar and high attenuation yeast in combination can really drive down FG. While I wouldn't completely trust the accuracy of the TILT with Krausen on it, I do trust it's stability at the end of fermentation. It appears that SG has only been at 1.002 for about 24 hours. I'd give it another day and call fermentation complete if the gravity holds.
     

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