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Old 04-04-2011, 10:01 PM   #1
Stelmica
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What is meant when people talk about counting the bubbles??

 
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Old 04-04-2011, 10:06 PM   #2
WIP
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It is an unreliable way of telling how vigorous the fermentation is. It refers to how many times the airlock releases air/co2.
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Old 04-04-2011, 10:07 PM   #3
Scut_Monkey
 
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Most likely they are talking about counting the bubbling on the airlock. Also known as airlock activity. It's a crude way to determine if fermentation is going on by the release of CO2.

 
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Old 04-05-2011, 11:48 AM   #4
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Why do you say "unreliable"?. I always find it a great reassurance to see bubbling a few hours after pitching my yeast.
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Old 04-05-2011, 11:50 AM   #5
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Aaaaaaaand here comes revvy!
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Old 04-05-2011, 12:39 PM   #6
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Quote:
Originally Posted by Brew_Master
Why do you say "unreliable"?. I always find it a great reassurance to see bubbling a few hours after pitching my yeast.
Its unreliable because bubbling can happen without it being fermentation, and fermentation can happen without you seeing bubbles. Sounds unreliable to me.
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Old 04-05-2011, 01:17 PM   #7
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Quote:
Originally Posted by discnjh View Post
Its unreliable because bubbling can happen without it being fermentation, and fermentation can happen without you seeing bubbles. Sounds unreliable to me.
Ditto. The wort can release dissolved CO2 causing airlock activity that is misleading. On the other hand, unless the fermenter is air tight the airlock may not move at all when fermentation is actually happening. The best way to monitor fermentation is with SG readings. However, airlock activity is a CRUDE way to monitor fermentation.

 
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Old 04-05-2011, 04:00 PM   #8
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Quote:
Originally Posted by Scut_Monkey View Post
On the other hand, unless the fermenter is air tight the airlock may not move at all when fermentation is actually happening.
Well that's the point of an AIRLOCK to make the fermenter airtight, and yeah I know it can't be as reliable as an SG reading but you have to wait a day or two between readings to tell if activity has ceased but usually if there are no bubbles that's an instant hint that fermentation has stopped or is really really slow
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Old 04-05-2011, 04:02 PM   #9
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And usually after degassing there should be no more CO2 to bubble.

 
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Old 04-05-2011, 04:28 PM   #10
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Quote:
Originally Posted by Brew_Master View Post
Well that's the point of an AIRLOCK to make the fermenter airtight, and yeah I know it can't be as reliable as an SG reading but you have to wait a day or two between readings to tell if activity has ceased but usually if there are no bubbles that's an instant hint that fermentation has stopped or is really really slow
Exactly. Its a hint. Not a guarantee of anything, and that's the point people are trying to make when they say the airlock is an unreliable sign of fermentation.

In order to see airlock activity for a given fermentation, all of the following must be true:
1) fermentation occurs, producing CO2
2) fermenter is sufficiently sealed so that CO2 has no significant escape path other than through the airlock/blowoff tube
3) you happen to check the airlock for activity frequently enough/long enough/at the right time to witness the release of CO2

So if you didn't quite seal your fermenter, or you just happen to check at the wrong times, you can certainly go through a completely successful fermentation without ever seeing a bubble.

In addition, there are a number of things that could cause airlock activity outside of active fermentation, the most common of which are probably:
1) your fermenter warmed up a little, and the gas in the vapor space expanded, building pressure and causing gas to vent
2) your fermenter warmed up a little, resulting in gas coming out of solution, since gas is less soluble at high temperatures.

So yes, airlock is a hint. If you had two fermenters sitting next to each other and one had a bubbling airlock and one didn't, and you had to guess which one was actively fermenting, you would guess the one with the bubbling airlock, for sure. But airlock activity is not a sure fire sign one way or the other, and the reason this gets stressed on this board is because of the large number of "OMG, my beer isn't fermenting" threads that end up with "oh, it turns out everything was fine. :-D

 
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