Home Brew Forums > Home Brewing Beer > Fermentation & Yeast > Never ending fermentation? 11 days in primary and still bubbling once every 5 sec
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Old 02-18-2011, 07:19 AM   #41
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In general, it is better to weigh the amount of DME added rather than using cup measurements. One cup may not actually be one cup if it is not well compacted. This can offset your starter gravity and therefore the health of the yeast.
I too prefer measurements like millilitres and grams but how do you convert a cup to weight for DME?
Reason I ask is I was looking at the FAQs on WhiteLabs site and they recommend 1 cup DME to 2 pints of water for starters.


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Old 02-18-2011, 11:00 AM   #42
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I too prefer measurements like millilitres and grams but how do you convert a cup to weight for DME?
Don't need to. Just use a 10:1 ratio. 1000ml water:100g DME, 2000ml:200g etc...


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Old 02-19-2011, 07:09 AM   #43
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Default Volumes vs Weight of DME

Thanks. Yes I had seen that ratio posted by many experts which made me wonder why WhiteLabs would talk volumes for DME rather than weight. Guess they figure some brewers may not have digital scales just volume measures.
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Old 06-01-2015, 02:05 PM   #44
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People always preaching this thing about bubbles and fermentation are two different things and that the only accurate gauge to know whether fermentation is finished or not , is by taking a hydrometer reading. Well, that is very true, but why risk the chance of air getting in your fermenter by running multiple hydrometer tests. Bubbles, are CO2 and CO2 is a direct by-product of fermentation, so don't tell me that airlock bubbles and fermentation are two different things
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Old 06-01-2015, 02:14 PM   #45
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Well, that is very true, but why risk the chance of air getting in your fermenter by running multiple hydrometer tests. Bubbles, are CO2 and CO2 is a direct by-product of fermentation, so don't tell me that airlock bubbles and fermentation are two different things
I think CO2 keeps being released well after fermentation has ended. I recently split a large batch and used S04 in one and S05 in the other. S05 kept bubbling even after it reached its terminal gravity and was still bubbling (albeit slowly) when I bottled, more than 2 weeks after pitching. The beer has come out fine so I know I didn't bottle too early.
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Old 06-01-2015, 02:18 PM   #46
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Bubbles, are CO2 and CO2 is a direct by-product of fermentation, so don't tell me that airlock bubbles and fermentation are two different things
While you're right that the bubbles are CO2, the issue is that there are multiple reasons for why that CO2 is coming out of the airlock rather that just staying in the fermenter.

During fermentation, the CO2 exits through the airlock because the pressure inside the fermenter exceeds the outside air pressure. So the CO2 gets "pushed" out the airlock.

But the mistake you're making is in assuming that fermentation is the only cause of a pressure differential. If the pressure outside the fermenter decreases (such as when a low pressure weather front passes over your area), then the pressure inside the fermenter will be relatively higher than the air outside of it. CO2 will vent out the airlock to equalize the pressures again, even though no fermentation is actually occurring.

Likewise, if the temperature of the room containing the fermenter warms up, this will produce a drop in air pressure (warm air is less dense than cold air). Again, CO2 will vent out of the airlock until the pressures inside and outside of the fermenter are equal again.

So, yes, a gravity reading is the only way to know whether or not fermentation is still occurring. A bubbling airlock does not necessarily mean the yeast are producing CO2.


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