stalled fermentation?

[Dorkusmalorkus]

Is it possible to tell if fermentation has stalled by the way it looks?

I used a balloon as an airlock and let it ferment until the balloon went completely limp. Two days ago I tranfered it to another jug and put the balloon airlock on it.

The small fermentation bubbles are no longer visible, but the liquid is still cloudy and the balloon becomes inflated again when the jug is shaken slightly.

 

[bernardsmith]

Short answer, Dorkusmalorkus is , No. Not possible.
The only reliable way to determine whether fermentation is still ongoing or has stalled is to measure the specific gravity over time and observe if the gravity is falling or has not budged. If the gravity is above .996 and is dropping then it has not stalled. If it is above 1.000 and has not moved in say 3 days then it has stalled. (if the gravity is below 1.000 and has not moved then for all intents and purposes the fermentation has not stalled but has ended as there is really no sugar left for the yeast to ferment).

Whether a balloon inflates or lies limpid or whether there are bubbles in an airlock or not really tells you next to nothing unless you are certain about the amount of fermentable sugar still in the liquor; the quality of the seal between the glass and the plug, you understand how changes in ambient air pressure can affect how CO2 is expelled from the wine, how liquids hold gas when temperatures rise and fall or how particles dropping out of suspension cause gas to nucleate. In short, there are just too many variables involved to be able to use how full a balloon is or isn't to determine whether you have a problem. An hydrometer is needed.