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Old 09-11-2009, 04:12 PM   #1
May 2009
Posts: 138

How soon during fermentation phase should one take a hydrometer reading? My brew is in its primary stage and has been sitting in the carboy since 1:30ish am 9-8-09.

Primary 1 - Nothing
Primary 2 - Nothing
Secondary - Nothing
Aging - Nothing
Bottled - Nothing
Keg 1 - Delirium Tremens Clone
Keg 2 - Air
Future - Oatmeal Stout?

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Old 09-11-2009, 04:14 PM   #2
Apr 2009
Peoria, IL
Posts: 166
Liked 2 Times on 2 Posts

I'm far from a seasoned veteran, but I generally wait about a week to see if it's near the expected FG (final gravity). If so, I wait until a day or 2 before I plan to bottle to take another. If it hasn't changed then I prime & bottle. Otherwise, wait another few days and check again.

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Old 09-11-2009, 04:16 PM   #3
SamuraiSquirrel's Avatar
Jun 2009
Aurora, IL
Posts: 583
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Some people take a few hydrometer readings throughout fermentation. Personally, as long as you have signs of fermentations within a day or two I wouldn't even bother taking a reading until you are ready to bottle it.

Take a reading on bottling day to make sure your gravity gives you a green light to bottle and you should be good to go.

A week in the primary should get you pretty close to F.G. There are some benefits to letting it ferment longer though. I typically leave them three weeks in the primary and then bottle.

I don't take a gravity reading until bottling day on week 3.

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Old 09-11-2009, 04:25 PM   #4
Aug 2009
Lansing, MI
Posts: 25

I usually don't take my first reading until after a week in the primary. Then when its getting close to bottling time I take two or three readings on consecutive days to make sure fermentation is complete (ie gravity isn't changing) before I bottle.
Primary: (empty)
Secondary: Chshre's Double Chocolate Oatmeal Stout
Conditioning: Sweet Cider
Drinking: Yuri's Thunderstruck pumpkin ale

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Old 09-11-2009, 04:27 PM   #5
david_42's Avatar
Oct 2005
Oak Grove, Oregon, USA
Posts: 25,599
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A week to two weeks.

Or you could take a sample and sit it next to the fermenter and have continuous monitoring.
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Old 09-11-2009, 04:43 PM   #6
Arkador's Avatar
Apr 2009
Fort Worth, TX
Posts: 1,702
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Originally Posted by david_42 View Post
A week to two weeks.

Or you could take a sample and sit it next to the fermenter and have continuous monitoring.

minimum 1 week, even though visable signs may end in 3 days, the yeast is still at work.

A sample would ferment at a different pace. I saw Revvy post about that before also...

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Old 09-11-2009, 05:40 PM   #7
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Feb 2008
Reed City, MI
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I had my Wit in the basement for 1 week and brought it up to finish and took a reading. Still not done. Plus, the cooler basement allowed a percentage of CO2 to remain in solution, and the sample took a LONG time to decarb. It was only about 10 degrees cooler.

I'm giving it another week to finish before checking again. Then maybe another week to condition and settle before I keg.

But different beers and yeasts act differently so it might be done in 1 week for you, or maybe several. That is why the hydrometer is so important.
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Old 09-11-2009, 05:58 PM   #8
tdavisii's Avatar
Jan 2007
St. Louis
Posts: 714
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Really how many hydrometer readings you take is completly up to you. Most of the readings will show you what you already know is happening. ITS FERMENTING. Most of us are highly inpatient and just want to get involved when we should just relax and have a icee beverage instead of screwing with our brews. So my advice is to wait as long as you want take as many hydrometer readings as you want but keep in mind that fermentation takes awhile.

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Old 09-11-2009, 06:14 PM   #9
Hang Glider
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Hang Glider's Avatar
Mar 2007
North Augusta, SC
Posts: 3,218
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Having brewed for about 8 years now, I've finally developed a bit of patience.

I take my hydro reading on brew day, as it goes into the fermenter, just to see how close I am to my target. Then it sits in the corner, in my fermentation chamber for 3-4 weeks, longer for my heavier beers. Then, I usually rack to a secondary for about 2 more weeks, again, heavier beers - longer. I never take another hydrometer sample during this whole time.
When I'm finally ready to bottle or keg, I take the reading - I've never had to re-pitch yeast, (perhaps I'm lucky, but perhaps I'm just giving the yeast time to do it's job). My final gravity is usually close to the predicted value, and it tells me my ABV. Then into the keg or bottles for 3 more weeks before I even think about sampling. 2 more weeks before I share with anyone.

yes, that's about 8 weeks minimum (for me), from brew day to drinking...

so, how soon should you? who knows.... but waiting and temperature control have served me well.

Welcome to your new hobby!

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Old 09-11-2009, 10:49 PM   #10
Aug 2009
East Bay, CA
Posts: 11

If I could piggyback onto this question, since mine is very similar, here goes.

I usually do a partial mash where i add 1/3 of my wort to water in the fermenter, pitch yeast and then add the rest of the wort and cap off the fermenter. My question is (a) should i do an initial hydrometer reading and (b) if so, when do i take the reading?

Do I risk pulling out too much yeast if I take a sample right before capping off the fermenter? I assume that I need to do a hydrometer reading on the wort + topping off water, as opposed to the wort alone.


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