Brew that is not Fermenting:
After yeast was added and after two days nothing has happened:
The first cause could be that of a leaking fermenter. If the bubbler airlock is not bubbling or shows no sign of activity, it could very well be due to the insufficient sealing between the lid and the fermenter. Although there may be fermentation, the carbon dioxide is not exiting through the airlock. Another possible cause could be that the yeast that was used is not favourable. Perhaps it is expired or bad yeast. Yeast is a live culture, a living creature for that matter and needs to be treated with special care. Be sure to avoid using yeast that is too dry. A solution to this problem is to re-hydrate the yeast in normal water. It is also recommended to refrigerate your yeast so that it does not die from been exposed to too much heat.
Another possibility as to why your brew is not fermenting could be because the fermentation conditions may not be favourable. i.e: it’s far too cold. Most ale yeasts tend to go dormant below 15 °C. Also, if the yeast was first re-hydrated in warm water then pitched into an ice cold brew, this could shock the yeast and it will take longer for it to adjust and ferment. A solution is to heat the entire brew by a just a little – it make all the difference to wake up those little yeasty cells!
Finally, another possibility could very well be as a result from the very start of your brew, i.e: poor sanitization. Sanitization is always key when it comes to brewing, therefore, it is essential that your brewing equipment, including your fermenter, is sterilized to perfection! However, if you sanitized too well, it can also have negative effects on your brew. For example, if you are preparing the warm water to rehydrate your yeast starter and you do not cool it to the correct temperature, the yeast can either go sluggish to rehydrate if it is too cold and if it is too hot, the yeast will do nothing to the wort. However, do not despair for there is a solution! All you’ll have to do is pitch new yeast at the correct temperature.