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Stuck fermentation after two weeks

AG or extract? Use the US-05? What temp are you fermenting?

DO NOT AERATE AT THIS POINT. If you think it’s stuck you can try warming it up a little a little and gently rousing the yeast. If that doesn’t work and you want to pitch more yeast then you have to pitch a really active starter.


Warm it up a bit. Most the time. Around this time fermetation should slow down. You could shake the fermentor a bit. Or you did underpitch but i would not add more yeast at this time

I agree with @loopie_beer. I would NOT shake the fermenter or aerate the beer in any way. You’ll oxidize and ruin it.

If it’s extract it could just be done. If you want to pitch more as Loop said you should make a starter and let it get to high krauesen before pitching.

My friend just brewed that recently. I think his ended around 1.020

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How do you know it’s stuck and not finished? You need to do a forced fermentation test. If that shows no more fermentables, then all the yeast in the workd won’t help!

I don’t know what a forced fermentation test is. I did a all grain everything went fine was a little low on the OG but not bad. If you have the time @denny would you go through the test for me? Thanks Scott

Here’s what I found (I hadn’t heard of it either):

Essentially, take a small bit of your beer, add an absurd amount of yeast, see if it helps. If it doesn’t no amount of yeast you add to your beer will take off any more points.

Yep, that’s pretty much it. Put maybe a cup of beer into a clean container. Add a crapload (technical term) of yeast…ANY yeast, even bread yeast will work. You want to see if there’s any possible way it will ferment further. If it does, you know you have fermentables left and you can pitch more yeast into your fermenter. If it doesn’t, all the fermentables are used up and adding more yeast won’t help. FWIW, I think that’s what’s going on with you.


Just a long shot but I have to ask, you are using a hydrometer not a refractometer?

@denny I understand that many things factor attenuation he is only hitting around 60%. That’s pretty low.

How did you mash? How long? What mash temperature? How accurate is your thermometer? You may have just created a less fermentable wort.

I mashed using BIAB, 75 min, @154. I have a thermo pen, hit my ph @ 5.3. I thank everyone for their input, I’m going to try the test @denny told me about see what happens.

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Yeah, but that doesn’t necessarily mean it isn’t done.

Only way a hydrometer test. To find it out

However, that won’t tell you if there are still fermentables left

Ok did what you said and I got a slight fermentation then stopped so I guess it’s done. Thanks @denny for the advice, and thanks to everyone for your input.


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Slight meaning what? What was the FG of the sample?

But you take a og reading and fg reading. At least 3 times a reading. During the fermenting. So now my question. If several readings are the same. Its either done. Or indeed stuck. Fermentabels left. But how you know for sure ? One thing i start doing. I started. To add oxygen to my wort. Before i pitch the yeast. Seems to work

You know for sure by doing a forced fermentation test. I do not add O2 before pitching and I don’t get stuck ferments.

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