First Batch - Bottling Specific Gravity?

I brewed my first batch exactly 1 week ago today (Lake Pepin Porter). When I checked the specific gravity before fermentation it was 1.046. Today it is 1.020. How much longer should I let it ferment? I know you guys say 2-3 weeks, but what SG should I be looking for? I'm a little confused.

Thanks for the help!

You let it ferment until it is done....it's not something you control. You let your beer ferment as long as it takes to finish. That's not something you control, a beer takes as long as it needs, it could be days or a week or more. That's not the same as leaving a beer in primary, or racking to secondary (which you should do AFTER fermentation is complete as well). But the yeast have a job to do and you need to let them do it, and they follow any calendars.

You determine when a beer is finished by taking two consequtive grav reading over a 3 day period. I usually recommend take the first reading on day 12 and the last on day 14 if planning to secondary.

Your recipe should give you a range of final gravity that it should reach. But they don't always reach them- hence making sure the gravity is stable over 3 days.

borovy3488 said:

I brewed my first batch exactly 1 week ago today (Lake Pepin Porter). When I checked the specific gravity before fermentation it was 1.046. Today it is 1.020. How much longer should I let it ferment? I know you guys say 2-3 weeks, but what SG should I be looking for? I'm a little confused.

Thanks for the help!

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The key is not the exact SG- it's when the SG is stable and not changing over the course of at least three days.

So, since it's only a week old, check the SG again about two days before you want to bottle. If it's still 1.020, then it's fine to bottle. If it's a bit lower, wait again at least three days before checking it.

Generally, a beer like that should be at terminal gravity by one week. However, that is not always the case, depending on yeast, factors from the mash of the extract (I assume you are using extract), temperature of your fermentation, etc.

Assuming you used a typical ale yeast for a porter, be sure it is fermenting in an area that is in the high 60s (68ish), maybe give your fermenting vessel a slight swirl, and wait another 2 weeks before checking again. I doubt you have anything to worry about.

Yooper said:

The key is not the exact SG- it's when the SG is stable and not changing over the course of at least three days.

So, since it's only a week old, check the SG again about two days before you want to bottle. If it's still 1.020, then it's fine to bottle. If it's a bit lower, wait again at least three days before checking it.

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Thanks for the help! That's exactly what I'll do. When should I shoot for bottling? Next Saturday?

Well, fermenting the beer is just a part of what the yeast do. If you leave the beer alone, they will go back and clean up the byproducts of fermentation that often lead to off flavors. That's why many brewers skip secondary and leave our beers alone in primary for a month. It leaves plenty of time for the yeast to ferment, clean up after themselves and then fall out, leveing our beers crystal clear, with a tight yeast cake.

So many of us leave our beers in primary for a month, then bottle. The longer you hold off the more time you give to the yeast to eliminate those things that cause off flavors in your beer, and will help make it clearer. I know it's your first batch and you're anxious, but the longer you wait, the better tasting beer you will ultimately have.

Revvy said:

Well, fermenting the beer is just a part of what the yeast do. If you leave the beer alone, they will go back and clean up the byproducts of fermentation that often lead to off flavors. That's why many brewers skip secondary and leave our beers alone in primary for a month. It leaves plenty of time for the yeast to ferment, clean up after themselves and then fall out, leveing our beers crystal clear, with a tight yeast cake.

So many of us leave our beers in primary for a month, then bottle. The longer you hold off the more time you give to the yeast to eliminate those things that cause off flavors in your beer, and will help make it clearer. I know it's your first batch and you're anxious, but the longer you wait, the better tasting beer you will ultimately have.

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Will do. I am very anxious to taste my first brew, but I want it to be as good as possible. I'll wait a month, then bottle. Thanks for all of the tips. Glad I found this place.