How do you know when its done fermenting?

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splinterz169

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So I have a 5 gallon batch of beer that I think is almost done. You can still see it fermenting small bubbles but its not really doing enough to make any bubbles in the gage on top... Maybe goes once every couple of minutes. How do I know for sure?
 

J187

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The airlock doesn't matter at all. They bubble sometimes when basic fermentation is done, and sometimes they don't bubble even though fermentation is happening.

Take a gravity reading... if it's near your expected FG and it stays constant for a few days, fermentation is done.
 

ShaineT

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Most ales are done in 5 or 6 days but the yeast needs some more time to clean up and settle. You truly don't know without taking a reading with your hydrometer. If it stays at the same SG over a few days without dropping then its likely done. If you're not taking a gravity reading its usually recommended to leave it in primary for at least 3 weeks. Best of luck :)
 

FATC1TY

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Like mentioned, please do not gauge any level of fermentation based off an airlock. It can bubble for no reason even with simple changes in temp.

Use your hydrometer, and take a sample, and check the gravity. Don't put the sample back in the primary fermenter by the way. If it's at, or close to your expected final gravity, then give it another 3 days, and check it again. If it's the same, then it's more than likely done.
 

glick

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So I have a 5 gallon batch of beer that I think is almost done. You can still see it fermenting small bubbles but its not really doing enough to make any bubbles in the gage on top... Maybe goes once every couple of minutes. How do I know for sure?
Hydrometer reading :mug:
 

BigFloyd

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If you don't have a hydrometer (which you should), give it 3 weeks in the primary.
 

unionrdr

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If you don't have a hydrometer,get one. Cheap insurance against guessing & bottle bombs. My ales usually take a lot more than 5-6 days to completely ferment out. Then when FG is reached,give it another 3-7 days to clean up & settle out clear or slightly misty.
 

zinn

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So, if you completely screwed up and didn't take an original gravity reading . . . how do you know when it's done fermenting? I'm making a pumpkin ale with Safale-05.
 

GoodTruble

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So, if you completely screwed up and didn't take an original gravity reading . . . how do you know when it's done fermenting? I'm making a pumpkin ale with Safale-05.
You only need an OG to calculate abv (and efficiency). You don't need it to determine if fermentation is done. If it has been 5-7 days, and you think fermentation is done, take gravity reading, then take another 3 days later. If the gravity holds steady, it's probably done.

Also, there are several brewing apps/websites where you can enter your recipe and get a reasonable estimate of what you final gravity will be. (Or you can just post the grain bill and yeast here, and I bet people can give you a pretty safe range for your expected final gravity). But that's just a guide, you will still need two consistent gravity readings to be sure.
 

RM-MN

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You only need an OG to calculate abv (and efficiency). You don't need it to determine if fermentation is done. If it has been 5-7 days, and you think fermentation is done, take gravity reading, then take another 3 days later. If the gravity holds steady, it's probably done.
If it has been 8 to 10 days from pitching yeast and the gravity is stable, the beer probably still isn't ready to be bottled or kegged. Given more time, the suspended yeast and trub will settle out and the beer will become cleaner and better tasting. One of my best tasting beers spent 9 weeks in the fermenter. That let a higher percentage of the particles to settle out in the fermenter and not get transferred to the bottles.
 

BrewnWKopperKat

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You only need an OG to calculate abv (and efficiency). You don't need it to determine if fermentation is done. f it has been 5-7 days, and you think fermentation is done, take gravity reading, then take another 3 days later. If the gravity holds steady, it's probably done.
It is common to use OG, along with estimated yeast attenuation, to estimate FG (or a range for FG).

With an estimated range for FG, one can detect a stuck/stalled fermentation as well as possible contamination.

If FG stable and is in the range, it's probably done.

If FG is stable, but outside the estimated range, there may be a need for some additional investigation to determine if 1) it's done or 2) fermentation has stalled or 3) the batch may be contaminated.

With a "new" yeast strain or a new recipe, a "Fast Ferment Test", done concurrently with the actual fermentation, would be an interesting way to assess the wort's fermentability and provide insight into the attenuation estimate that was used for the recipe.
 

GoodTruble

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If it has been 8 to 10 days from pitching yeast and the gravity is stable, the beer probably still isn't ready to be bottled or kegged. Given more time, the suspended yeast and trub will settle out and the beer will become cleaner and better tasting. One of my best tasting beers spent 9 weeks in the fermenter. That let a higher percentage of the particles to settle out in the fermenter and not get transferred to the bottles.
Agreed. I just meant fermentation (sugars turning into alcohol) would probably be complete. Waiting even longer can also have more benefits.
 
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zinn

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You only need an OG to calculate abv (and efficiency). You don't need it to determine if fermentation is done. If it has been 5-7 days, and you think fermentation is done, take gravity reading, then take another 3 days later. If the gravity holds steady, it's probably done.
Thanks! Assuming it has been at least 5-7 days, can I do any harm to the beer by removing the airlock and taking a quick gravity reading? I assume I'll still need to sterilize anything that touches the beer, but is there anything I should be sure to do for this process?
 

hotbeer

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Has your beer cleaned itself up? Why check for FG if it isn't anywhere near cleaned up? Any air you let in is potential for oxidation and less hop flavor.

IMO, FG can be reached in just a few days. However it takes about two to three weeks before the beer cleans itself up enough to be worth bottling. Though if you are in a hurry, you can do stuff to clarify it like cold crashing, gelatin and other such.
 

GoodTruble

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Thanks! Assuming it has been at least 5-7 days, can I do any harm to the beer by removing the airlock and taking a quick gravity reading? I assume I'll still need to sterilize anything that touches the beer, but is there anything I should be sure to do for this process?
Sterilize whatever touches the beer. And try to keep outside air/oxygen from getting in. But other than that, it should't hurt the beer. But don't put hydrometer directly in the fermenter (too many things can go wrong). If you want to get a gravity reading, remove a sample.
 

Wables

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And after you take the gravity, drink the sample. It will be warm and flat, but over time you will learn a lot about where your beer is at by how it tastes.
 

Oleson M.D.

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General rule-of-thumb, 3 to 4 weeks time. We allow the beer to ferment for a minimum of 3 weeks, sometimes 4 weeks.
Then cold crash for another 3 to 7 days. Works for us.
 

odie

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without knowing what kinda beer you made, yeast, temperature and how long it's already been...no way to even guess how long it should take.
 

GoodTruble

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And I think there is an argument to be made that newer brewers may benefit from quicker turnaround times. The more you brew, the more you will learn.
 

hotbeer

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And I think there is an argument to be made that newer brewers may benefit from quicker turnaround times. The more you brew, the more you will learn.
My 1 gallon all grain brews let me keep several fermenters going all the time and still I have to buy beer at the store.

So they have taught me the value of patience with any one batch to give it the needed time they need. But since I won't have to ever worry about having too much beer, I can start a batch every few days. So I can quickly experiment with procedures that maybe didn't work well the time before or try new things.

I'm only limited by the number of fermenter vessels and space to keep them in a somewhat temp controlled environment.
 

zinn

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without knowing what kinda beer you made, yeast, temperature and how long it's already been...no way to even guess how long it should take.
It's a pumpkin ale using Safale US 05. It's been fermenting at about 68 degrees. It's only been fermenting 4.5 days.

Maris Otter Pale (7.5)
Munich 10 Lovibond (2.1)
CaraHell (0.21)
C-20 (0.315)
C-45 (0.21)
Special B (0.42)
Magnum (0.5)
Rice hulls
Safale US 05
 

trarmer007

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Safale 05 has attenuation at 78–82% - lets split and say 80%

Calculate OG since there was no measurement:

Maris Otter = 1.036 X 7.5 = 1.270
Munich - 1.035 X 2.1 = 1.070
CaraH - 1.034 X .21 = 1.007
Crys20/45 - 1.034 X .525 = 1.018
Special B - 1.036 X .42 = 1.015
Total = 1.380/5 gallons = 1.076 now reduced by your efficiency loss (estimated 75%) = 1.057 est. theoretical OG

Calc. FG by: 1+ (57 X (1- .80 attenuation)/1000)) = 57 X .2 = 11.40/1000 = .0114 + 1 = 1.011

So, after 7-10 days, take a gravity reading. If you are at 1.011 (or close based upon OG, att. variation, malt variation, etc.) you can have confidence you're yeast ate all you served it. Take a 2nd gravity reading a day or two later. If the reading is the same, you know you're done.
 

odie

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It's a pumpkin ale using Safale US 05. It's been fermenting at about 68 degrees. It's only been fermenting 4.5 days.
tasty but I meant the OP's beer...lol
 

Mutant

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I had a Doppelbock that was already lagering on secondary when I realized that it hadn't fermented out and the FG was 1.025. I raised the temperature back into the 50s and fermentation started back up. I'm waiting for my son to draw a sample tonight or tomorrow to see what the result is now. I hope I saved the 13.2 gallons and didn't make it worse. I at least know this continued fermentation process didn't incur any oxidation.
 
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Short answer.. Its alive! It is never done till you either KILL IT, or drink it. :)


Use a hydrometer, take a reading... wait 3 days and take another. If it hasn't changed.... MONEY! :)

Cheers
Jay
 

Yooper

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Has your beer cleaned itself up? Why check for FG if it isn't anywhere near cleaned up? Any air you let in is potential for oxidation and less hop flavor.

IMO, FG can be reached in just a few days. However it takes about two to three weeks before the beer cleans itself up enough to be worth bottling. Though if you are in a hurry, you can do stuff to clarify it like cold crashing, gelatin and other such.
It certainly does NOT take three weeks to "clean up". That's not even close to the reality. If the FG is at, well, FG, it's done. It won't get "doner" by sitting.

I personally do NOT use clarifiers or things like gelatin, and I keg or bottle my beer at day 10-17, depending on what I"m making. I would challenge others to make a clearer, crisper, more finished beer.

Doing what you advise is great, if it works for you! However, it's not correct to give statements that 'you have to do this for XX weeks, don't take an SG reading because you'll oxidize the beer", etc.

Yeast will finish that "clean up" phase within about 24 hours of reaching FG. Then the beer will start to clear. That's an ideal time to package, when the beer is clear or clearing. That can be in 7 days, or 20 days. However, the beer is done fermenting when it has been at final gravity, as seen with a hydrometer, for at least 24 hours.

If it takes three weeks in a fermenter for the beer to be acceptable, there is a problem with process, technique, or ingredients. It can be packaged when it is ready, and it's usually within 14 days.
 

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Thanks! Assuming it has been at least 5-7 days, can I do any harm to the beer by removing the airlock and taking a quick gravity reading? I assume I'll still need to sterilize anything that touches the beer, but is there anything I should be sure to do for this process?
Certainly do sanitize (not sterilize, unless you have an autoclave and can actually sterilize) anything that touches your beer. Take the reading, and don't pour back into the fermenter. Do not splash or agitate the fermenter or beer at all. If the reading is where expected, take another one in at least three days. If the are the same, the beer is done! If it's starting to clear, it's ready to package. If it's cloudy, wait a bit and check for clarity in a few more days. Some beers won't clear (hazy IPAs), some will clear a little, depending on the yeast strain, and some will seem very clear. Than go from there.
Welcome to our obsession!
 

hotbeer

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It certainly does NOT take three weeks to "clean up". That's not even close to the reality. If the FG is at, well, FG, it's done. It won't get "doner" by sitting.

I personally do NOT use clarifiers or things like gelatin, and I keg or bottle my beer at day 10-17, depending on what I"m making. I would challenge others to make a clearer, crisper, more finished beer.

Doing what you advise is great, if it works for you! However, it's not correct to give statements that 'you have to do this for XX weeks, don't take an SG reading because you'll oxidize the beer", etc.

Yeast will finish that "clean up" phase within about 24 hours of reaching FG. Then the beer will start to clear. That's an ideal time to package, when the beer is clear or clearing. That can be in 7 days, or 20 days. However, the beer is done fermenting when it has been at final gravity, as seen with a hydrometer, for at least 24 hours.

If it takes three weeks in a fermenter for the beer to be acceptable, there is a problem with process, technique, or ingredients. It can be packaged when it is ready, and it's usually within 14 days.
For what ever reasons it does take me four to six weeks to get beer that I want to bottle. I don't use clarifiers either. I've watched them clean up almost to the point of looking like they are ready to bottle then get actively bubbling again which stirs up the bottom and clouds things up. Sometimes this happens several times.

Might be something I'm doing wrong. I am after all a noob at this. However some thoughts around here seem to just lead noobs into the idea that they must do something to immediately ready their current brew for bottling. All that's needed IMO is more patience. I just don't check SG or worry until after the beer seems to have ceased all activity and is clean.

Some of the suggestions to noobs seem like they are aimed at complicating the process and requiring one to throw more money at brewing. And that's fine with me if one want to do that.

I wouldn't have ever started brewing my own beer if I had to do all the fiddly stuff many do with their beers. All I'm doing is telling them they don't have to go by a timetable and that patience will result in a decent beer.

As for not taking SG readings or you'll oxidize your beer, that's not the reason for anytime I suggest one don't take SG readings. It's because it's ridiculous IMO to take a reading every day if one has to remove a sample. I'll always be of the opinion that if the beer isn't cleared up, then there is no point in taking an SG at all.

If it takes three weeks in a fermenter for the beer to be acceptable, there is a problem with process, technique, or ingredients. It can be packaged when it is ready, and it's usually within 14 days.
Might be. I'm a noob and still learning. However all too often noobs with concerns seem to be hit with suggestions that only seem to cause them more anxiety with their current brew. I see no fault for me trying to tell them that all they need is more patience. Not taking SG's and not thinking it must be bottled in a specific time period will let them have more patience IMO.
 
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