Need help with a stuck fermentation

[pumpkinman2012]

Here is the latest update:

02/07: SG 1.034
02/09: SG 1.032
02/14: SG 1.022

If it continues like this, I'll hit the target FG in 3-4 days.

 

[kiblerjd]

Keep on keepin on !!


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[BackAlley]

I'm always up for a friendly debate but I'm not motivated enough to sit down and do the calculations. I guess it's really all relative to how much activity he is seeing. I would love to see some gas law calculations on how much CO2 comes out of solution with a 5-10 degree temp change in beer that was under about 0.5" water column of pressure. I think it is negligible but like I said I'm lazy and still a little hung over from hitting the home brew too hard last night. Cheers.

Using the first graph that google turns up, I'm going to guess the solubility of CO2 in the beer will go from 0.030 g/kg to 0.025 with a 10F change. So that's 0.005 g/kg. Call it a 20kg batch so that's 0.01g. Density of CO2 is about 2kg/m3 so we release 0.005 m3. I converted that to 1000 teaspoons just to give a feel for that volume. That doesn't seem negligible to me.


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[kiblerjd]

Do you mind posting the link to the graph. I can't find a single one that shows pressure as low as it would be in a fermenter (call it 1 inch water column to be conservative). Everything I see starts at 5 psi. Either way I don't really care anymore and I hope nobody thinks I'm trying to argue.


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[BackAlley]

http://www.engineeringtoolbox.com/gases-solubility-water-d_1148.html



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[kiblerjd]

Check your math you are off by a factor of 1000. The final result is one teaspoon which is negligible. 2kg = 2000g therefore .01g/2000g = .000005m3 = 1tsp.


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[BackAlley]

Check your math you are off by a factor of 1000. The final result is one teaspoon which is negligible. 2kg = 2000g therefore .01g/2000g = .000005m3 = 1tsp.


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You're right I think. Does that mean that off gassing of CO2 is an urban legend or was my solubility wrong?

And thanks for checking my math.

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[kiblerjd]

I'm sure there is a stage in fermentation after really active primary where the CO2 that was in solution is going away. My whole point was that if fermentation is stuck and you raise temp there is basically nothing but fermentation that is going to cause active bubbling that you actually notice.

I don't think it's completely urban myth but I think there are very specific times when you would see it. If you shake a fermenter that is in primary fermentation it goes ape $hit. Do that to a beer in secondary and nothing really happens.

I have alway prescribed to what I said earlier which is that no bubbles doesn't necessarily mean you are at FG but active bubbling does mean the beer is fermenting.

Cheers everyone


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[kiblerjd]

Here is the latest update:

02/07: SG 1.034
02/09: SG 1.032
02/14: SG 1.022

If it continues like this, I'll hit the target FG in 3-4 days.

So what's the news man did you hit your FG?

 

[pumpkinman2012]

Hi!, I hit just above my FG, which is fine, it eventually went from potentially stuck at 1.040 down to 1.014, dry hopping as we speak, then it's off to cold crash and bottle.
Thanks again for all of the advice.