Newest Threads

**Homercidal** · 08-31-2009, 05:52 PM

I used to go by the airlock, until one time it didn't bubble and I very nearly pitched with an alternate yeast. I'm glad I didn't, because once I popped the lid to check with a hydro, I found the signs of fermentation. Somehow that lid didn't seal tight for the first time.

I very nearly pitched the wrong yeast as a backup (only yeast I had at the time). Now that I have more experience I know to check FG with the hydro, and for more than just to see if it's fermenting. It can tell me how much it fermented, and if it should be done (very closely)

I guess for some, the airlock is good enough. Not for me. Well, maybe in a carboy, but I mostly ferment in a bucket, where the chances of having a leak are much higher.

flyangler18 · 08-31-2009, 05:55 PM

Quote:

The co2 will no escape through the airlock until all the deadspace is filled.

This is a factor that I didn't consider! Goodonya for noting it.

I'd have to think that an adequate pitch of yeast into a well-oxygenated wort will fill a headspace quite quickly, probably within hours. If one were fermenting a 3 gallon batch in a 6.5 gallon carboy, this would be more of a factor.

**arturo7** · 08-31-2009, 06:04 PM

I thought this was the science forum?

Nothing here but anecdotal evidence.

Where is the science?

**ThickHead** · 08-31-2009, 06:08 PM

Quote:

Originally Posted by arturo7

I thought this was the science forum?

Nothing here but anecdotal evidence.

Where is the science?

Observation is a "scientific" method. Particularly when combined with the application of some form of established metric (like that associated with a hydrometer).

**AnOldUR** · 08-31-2009, 06:25 PM

Quote:

Originally Posted by flyangler18

This is a factor that I didn't consider! Goodonya for noting it.

So what, you suck all the air out of your carboy after you put the lid on?

From the very start of fermentation CO2 will be displacing the existing air and pushing it out the airlock. If you don't have a leak you have bubbles right from the start.

And I'm not saying that airlock activity is the end all choice of determining your beers condition, but it is the primary tool. A very low tech, but potentially accurate tool.

Tonedef131 · 08-31-2009, 06:31 PM

Quote:

Originally Posted by AnOldUR

So what, you suck all the air out of your carboy after you put the lid on?

From the very start of fermentation CO2 will be displacing the existing air and pushing it out the airlock. If you don't have a leak you have bubbles right from the start.

The head space only has to be pressurized enough to push the hat on the airlock out, but the liquid does have to become saturated with CO2 before it starts to release it. This will depend on the temp of the solution, so the warmer it is the less saturation will occur before it releases gas. This is a pretty minimal amount and it doesn't take long for the saturation to occur, but there is CO2 being produced before it starts pushing out of the airlock.

Evan! · 08-31-2009, 06:32 PM

Quote:

Originally Posted by AnOldUR

So what, you suck all the air out of your carboy after you put the lid on? From the very start of fermentation CO2 will be displacing the existing air and pushing it out the airlock. If you don't have a leak you have bubbles right from the start.

That's what I was going to say. Somehow I doubt that people have a vacuum in their headspace prior to fermentation.

Quote:

And I'm not saying that airlock activity is the end all choice of determining your beers condition, but it is the primary tool. A very low tech, but potentially accurate tool.

IMHO, it's a crude visual indicator that helps determine when to take a hydrometer reading. I use glass and BB carboys, so I usually rely on watching the wort more than I do airlock activity. I usually only take 2 or 3 readings. I have a refractometer, so I don't need to take anything prior to it going into the fermenter. I take my first hydro reading just prior to pitching; my second one is taken when I feel the bulk of fermentation has subsided (when the sugars are consumed, and it's transitioning into the conditioning stage). This is done to make sure I hit my target FG...if it hasn't, then I will either heat it up and stir, or I'll pitch onto another cake. I might also take one just before I rack to the keg, to make sure it's where I want it to be.

But just like Revvy's blanket statement that your airlock is unreliable, this blanket statement that it IS, is not helpful.

**ThickHead** · 08-31-2009, 06:32 PM

Quote:

Originally Posted by AnOldUR

...potentially accurate tool.

LOL...nice!

Trust your airlock, but trust your hydrometer more.

chumprock · 08-31-2009, 06:33 PM

Call me a nerd, but I'll stick to Hydrometer readings.

The parameters that qualify your statement are loose at best and I dont think can be guaranteed with typical homebrewing equipment.

flyangler18 · 08-31-2009, 06:43 PM

Quote:

So what, you suck all the air out of your carboy after you put the lid on?

From the very start of fermentation CO2 will be displacing the existing air and pushing it out the airlock. If you don't have a leak you have bubbles right from the start.

This is why I don't do science.

I'll stick with my artsy fartsy humanities stuff, thanks!