rtalbigr wrote:In the anaerobic phase the yeast is converting the sugars to alcohols, etc, and there is very little CO2 being produced so you are not going to see much air lock activity.
During the anaerobic phase the yeast convert sugar into CO2 and Ethanol and monitoring the amount of CO2 production is an indication of how aggressively the yeast colony is performing the task... I always see a lot of CO2 activity, sometimes with bubbles shooting several inches out of the wash, all the way to the very end of the fermentation process...
I wish I was better at documenting my research, but I tend to be rather haphazard. Anyway, check out this link:http://www.wyeastlab.com/he-yeast-fundamentals.cfm
From this you can see that the majority of the activity occurs during the lag and log phases, when O2 is present. Yes, alcohol is produced during the log phase but the principle activity is budding, growing the colony. With the O2 and most nutrients depleted the yeast enters the stationary phase which is anaerobic. Activity slows dramatically, especially CO2 production. Alcohol is still being produced and other chemical process are occuring. Depending on the wort, the yeast, temperatures, the stationary phase can last up to 10 days (with my meads it can last up to a month). Vigorous production of CO2 does not occur throughout fermentation.
With my AG worts I generally don't get much activity for the first 12-14 hrs. After that I will have vigorous air-lock activity for 24-36 (sometimes 48) hrs. Then is will start to slow. After about 3-4 days I generally will get a few bubbles every minute and that will eventually slow to where there is only enough pressure to hold up the cap. Generally after 6-7 days all activity ceases.
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