Primary indication of successful fermentation?

Is bubbling the best way to tell if fermentation is taking place?

Here is a side by side picture of 42 / 21 hours respectively.

Bubbling increased respectively 1.5 / 3 seconds.

If its bubbling that means the yeast is eating the sugar and producing CO2 and alcohol. Once the bubbling slows or stops, or slows you can take your hydrometer readings. If the readings don't change for three days, fermentation is complete.

The primary byproducts of fermentation are ethanol and CO2. This means bubbles in the airlock are a good indicator that fermentation is going on. However, like most things, presence might prove, but absence does not necessarily disprove. By this I mean, if you see bubbles and krausen you can be sure your yeast are active and working away, however, a lack of bubbles and krausen is not proof that your yeast are not working.

The best way to tell if fermentation is complete is to check gravity.

Unfortunately I am a complete rookie, and I didn't take the measurement before I started.... What can I expect to pay at my LHBS for the apparatus?

Also, thanks for the new vocab word; I was worried about the lack of krausen.

DeustchLehrer said:

Unfortunately I am a complete rookie, and I didn't take the measurement before I started.... What can I expect to pay at my LHBS for the apparatus?

Click to expand...

About $6 - $8 for a hydrometer, or $60 and up for a refractometer. Prices range wildly for refractometers based on quality, where purchased, etc.

Here is an example of a refractometer.

http://morebeer.com/view_product/18739

Yeah, bubbling is the best visual evidence of the initial phase of fermentation. The second best way is to observe the krausen that forms during this phase.

Sometimes there are leaks in the lid or in the airlock or blow-off tube. In those cases, the bubbling will not be seen...so looking at the krausen formation is the next best thing. It can happen in a day, or over 3 or 4 days; so it is easy to miss it. When that happens, the best way to know for sure is with a hydrometer test.

another indicator is cloudiness since you are using clear vessels. If you look carefully you will see what looks like specs getting churned around inside. While the yeast are too small for you to see with the naked eye large clumps of yeast and bits of trub can be seen churning away inside.