First of all, determine that your fermentation is really stuck and not just slow. My friend Rob has an interesting thing happening at his place. His yeast are apparently shy as a new cat or something because he never sees any bubbling in his air lock but his specific gravity readings are just fine and the beer tastes great. In his case, he simply has no visual indication of fermentation but it is happening. It could be that he does not have a perfectly sealed fermenter. I do not know what is going on with his system, but it is working, even if it is not perfect.
Obviously, the first step is to check your specific gravity readings. If they are too high and you have waited a week or so, your fermentation is likely stuck. I have never had my friend Rob’s problem, but I have had a delayed fermentation, where the yeast are apparently shocked or something, and the bubbling does not start for a few days. That is okay, as long as it fully ferments, but keep in mind that you should wait a week before determining that your fermentation is honestly stuck, since the bulk of the fermentation happens in the first week.
Here are some tings I have advised in the past to try to restart a stuck fermentation:
- Pick up the plastic primary fermenter by the handle and rotate your wrist to disturb the sediment on the bottom. This can revive some of the yeast that is under a layer of trub and get them interested in working again.
- Mix the beer thoroughly with a sanitized spoon or paddle to stir up the yeast at the bottom and get more oxygen into the wort.
- Make sure your temperature control is working. Yeast do not like large fluctuations in temperature. Also make sure that your fermenter is within the allowable temperature range for the yeast you are using.
- If these tricks do not start your fermentation, try adding another yeast packet or yeast starter. It could be that you got some old or bad yeast, or perhaps that the wort was too hot when you added the yeast and they died from shock.
Remember not to freak out if you get a stuck fermentation. There is nothing that cannot be fixed when it comes to brewing, as long as you are careful to avoid infection. Do you have a special trick you use when you have a stuck fermentation?