This occurs when your beer fails to ferment to completion. This can result from the use of old yeast or poor ingredients. The best way to take care of this problem, is to prevent it from starting. To do this, you should:
1. Re-hydrate the yeast by adding it to some water and adding wort to the yeast an hour or more before you pitch. This will help ensure that your yeast is still active.
2. Use an all malt or a recipe that has a lot of it, as yeast needs nutrients to stay alive. Corn and sugar lack these nutrients. If your yeast still fails to survive, it cannot reproduce. For this very reason, distilled water shouldn’t be used when making beer.
If you’ve used the proper amount of priming sugar and your beer is still flat, it’s probably due to the fact that you didn’t properly rise the sanitizing solution from the bottles. If too much sanitizer is left in the bottles, it can kill the yeast, which results in flat beer. The only way to prevent this is to stop it from happening.
Over carbonation can cause your beer to turn into a foam disaster. It can result from these causes:
1. Too much or uneven priming sugar. You should measure your primer carefully and dissolve it thoroughly in boiling water and allow it the proper time to cool. Before bottling, make sure to stir this into your beer.
2. Bottling your beer too early can also result in too much carbonation.
3. Poor sanitization is also a cause. If you allow your beer to come in contact with wild yeast, it can result in over carbonation and possibly even off flavors.
4. Bottles that are under filled can also contribute to over carbonation. You should allow 1/2 inch of head space to allow your beer time to pressurize.
By taking the proper time to fix problems, you’ll ensure that your brew comes out great every time you brew it. If you happen to run into a problem, always take the time to ration it off before you rush into fixing it. If you rush into fixing a problem, you may start another one.
You should expect problems, especially if this is your first time brewing. Even for expert home brewers, problems can occur from time to time — Which is something you’ll learn to deal with.