Fermentation problems is often something that home brewers experience. A common fermentation problem is simply that the would-be beer or wine never started fermenting. So before you give up and pour your homebrew down the sink, double check if the fermentation process actually hasn’t began. Judging fermentation by the bubbles (or lack thereof) out of the airlock can usually be deceiving.
Check for signs of fermentation:
Look at the beer (if it’s in a glass fermenter) or peek through the airlock hole in the lid (if it’s in a plastic fermenter). Do you see any foam or a ring of brownish scum around the fermenter? If so, the beer is fermenting or has fermented.
Use your hydrometer to check the gravity
The beer is typically done fermenting if the final gravity is 1/3 to 1/4 of the original gravity. For example: A 1.045 beer ferments down to 1.015 to 1.012 or below.
If after 24 to 48 hours fermentation has truly not begun — or you’re just not sure — try adding more yeast. (Situations like this one give you good reason to keep a packet of dry yeast in the fridge for emergencies.)
If fermentation still hasn’t begun after you add more yeast, you may have made one of the following mistakes:
- You didn’t rinse the sanitizer from the fermenter. Sanitizer residue can kill yeast, too. Be mindful of sanitary practices — how or when the beer ferments doesn’t mean a thing if you contaminate the whole batch in the process.
- You put the fermenter in a place that’s too cold. Leave it at 64 to 72 degrees Fahrenheit for Ales.
- You used old or dead yeast. The yeast contained in ingredient kits is often so old that it’s useless — always buy fresh yeast that has been kept refrigerated.
- You rehydrated the yeast improperly by using water that was too hot (more than 110 degrees Fahrenheit).Also, don’t leave the yeast in the rehydration water too long; 30 minutes is plenty.
- You used good yeast but shocked it with sudden changes in temperature or by adding it to wort that was too cold (under 70 degrees Fahrenheit) or too hot (over 110 degrees Fahrenheit). (Wort is unfermented beer; rhymes with dirt.)
You didn’t use enough yeast.
- Pitch 10 to 15 grams of dry yeast, or use 1 package of ready-to-pitch liquid yeast per 5 gallons of beer.
- Slow-starting or stuck fermentations usually mean under-pitching of yeast, under aerated wort, or both. To correct these problems in the future, pitch a larger volume of yeast and make sure you properly aerate the wort before pitching.
- High-gravity worst (those with a specific gravity of 1.056 or higher) need even more yeast and aeration for proper fermentation.
By Marty Nachel, Homebrewing For Dummies