Noob question about fermintation

[Chemlover123]

Hey! so I am working on my second batch of apple wine. I have read dozens of times that "airlock activity is not an indication of fermentation rate, blah blah blah" but no one has really explained how that can be true. To my understand of chemistry, CO2 production should be proportional to the rate of ethanol production:

C6H12O6 (glucose)--->2C2H5OH (Ethanol) + 2CO2 (Carbon Dioxide)

The reason i am asking this question is because my current batch is bubbling significantly slower then my first batch, and the SG hasn't shown much progress either (went from ~1.085->~1.083 after 2.5 days). So if an expert could explain to a scared beginner how CO2 production is not an effective indicator (quantitative explanation instead of subjective experience) if you be GREATLY appreciated!! thank you!

 

[nukinfuts29]

Beats me, I have never agreed with that whole airlock means nothing nonsense. Fermentation produces Co2, the more if produces to more you have coming out, the more bubbles. You can also count and track seconds between release in the airlock.

There's no reason you HAVE to use a hydrometer to monitor fermentation.

 

[LowerMillHillBackyardBrew]

This is all true, but I think this "airlock means nothing" thing comes from some facts:

CO2 can escape without any bubbles in the airlock, if there is a leak. Therefore there can still be fermentation even though you have a non-bubbling airlock.

Also, CO2 can get out through the airlock after fermentation is complete. For example, if the temperature rises. That will cause more CO2 to go out of the solution, and your airlock may bubble.

But yeah, overall bubbles in the airlock means there is something going on, and most likely it is fermentation, creating CO2, causing bubbles in the airlock.

 

[nukinfuts29]

This is all true, but I think this "airlock means nothing" thing comes from some facts:

CO2 can escape without any bubbles in the airlock, if there is a leak. Therefore there can still be fermentation even though you have a non-bubbling airlock.

Also, CO2 can get out through the airlock after fermentation is complete. For example, if the temperature rises. That will cause more CO2 to go out of the solution, and your airlock may bubble.

But yeah, overall bubbles in the airlock means there is something going on, and most likely it is fermentation, creating CO2, causing bubbles in the airlock.

If there is leak you have other problems.

Temp does affect co2 release but this is easily identified especially if you monitor airlock rate and temps daily in your brew log.

 

[DoctorCAD]

Put it this way...bubbles DO indicate fermentation, but lack of bubbles DO NOT indicate no fermentation.

 

[nukinfuts29]

Put it this way...bubbles DO indicate fermentation, but lack of bubbles DO NOT indicate no fermentation.

Well put, and this is an important note for new brewers to understand.

 

[Caveman911]

Had a similar issue... Day 8...temperature got down to 68 degrees and it seemed that the
Airlock bubbles came to a halt (less than one bubble per 20 seconds). Before that.. Temp was 76 degrees and bubbling every 5 seconds. Not worried though...we are still in business...I hope.

 

[muph]

CO2 can be building up at a very slow rate and you may not be able to watch it 24/7 to see it bubble every couple hours or so.