How do i know when my beer os done fermenting?

I am brewing my fist batch of beer and I am not sure how to tell of the fermentation is done or is finishing up. I don't want to take the instructions at face value because they say 1 week which seems a little short.

 

It's probably done at a week (meaning, the yeast have finished eating sugar), but I'd leave it for 2 weeks. The yeast continue to metabolize fermentation byproducts for a few days.

Do you have a hydrometer? Take a reading at 10-14 days or so, then take another one 2-3 days later. If they're the same, it means your gravity is stable and you can bottle it. Once it's stable, bottle when convenient.

 

This:
http://howtobrew.com/ Though you should really buy the book. Support the man and it's better anyways.

And this:
beer-and-wine-triple-scale-hydrometer

 

Many people just leave standard gravity beers in fermenters for 3 weeks, but the only way to know that a beer is done fermenting is to do what TyTanium said -- take gravity readings a few days apart. Once you get consistent readings, the fermentation is done.

But, you should still give the yeast some time to clean up after the fermentation is done. After they finish the sugars, the yeast will start processing certain compounds that they created during the initial fermentation (and some of these lead to off flavors).h

 

Yeah,I found that it takes on average 3-7 days to clean up by products of fermentation after it hits Fg. It'll settle out clear or slightly misty at this same time.

 

Thanks guys. I have a hydrometer so I will check it like that. Will leaving the yeast to clean up after themselves help make my beer more clear?

 

Yes. It'll clean up by products of fermentation & settle out clear or slightly misty in the 3-7 days on average it takes to do so.

 

The yeast cleaning up will not, in itself, make the beer clearer. It will make the beer taste better. But, at the same time that the yeast are cleaning up, the beer will start to clear.

 

I've watched this on a lot of batches. The yeast clean up by eating/converting fermentation by products. As they feed on these last tidbits,they settle out since there's nothing else left to eat. This is what I've been referring to all this time. It all happens at the same time from what I've observed.

 

In non-wheat beers I wait for the Krausen to fall out before taking gravity readings, usually starting at 14 days. Some will say that the best beer comes from sitting in the primary for a month, I'm usually not so patient. Young beer is still good beer if you aren't trying to win a competition with it. Instructions are often wrong, I got the most bizarre instructions with a German Marzen extract kit that I received for Christmas. 2 oz of specialty grains, 60 minute boil for mostly DME, a handful of hops added at 15 minutes left on the timer, no hops at 60 minutes. 2 week ferment and 2 week secondary on a lager, ferment at ale temps with lager yeast, no lagering stage. Sometimes you just have to throw the instructions in the trash and get recipes from people who actually brew.

 

I don't think we are disagreeing. The clearing is not a direct result of the yeast cleaning up the byproducts of fermentation. The "clearing" is from the yeast and sediment dropping out of suspension. My point was that the clean up and clearing aren't the same thing but tend to happen in tandem. But true clearing does not really happen for me until after the beer is in the fridge.

 

Yeah,we're basically in agreement. Both do happen at the same time,as there's no "food" left for the yeast after they metabolize fermentation by products,so they settle out.