Author Topic: How often do you check your gravity?  (Read 5390 times)

Offline cenosillica

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How often do you check your gravity?
« on: July 17, 2011, 02:00:17 PM »
I'm curious how often others are taking gravity readings.

Until recently, I have simply ignored it and waited 2 weeks in primary then 2 weeks in secondary to keg. Does anyone do daily gravity readings? For those who do check regularly, how do you prevent contaminating your fermenting wort?

Offline denny

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Re: How often do you check your gravity?
« Reply #1 on: July 17, 2011, 02:08:08 PM »
I wait until at least a week, often 2, then check it.  And if you can't take a gravity reading without contaminating your beer, perhaps you should consider taking up knitting for a hobby!  ;)
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Offline Thirsty_Monk

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Re: How often do you check your gravity?
« Reply #2 on: July 17, 2011, 02:36:23 PM »
I am taking reading every day after pitching just to make sure I have fermentation going.
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Offline pyrite

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Re: How often do you check your gravity?
« Reply #3 on: July 17, 2011, 03:37:33 PM »
I don't take gravity readings until I'm ready to transfer.  But I've been using the same brewing method, fermenting technique, and the same 5 yeast strains for the past couple years, and can accurately estimate how those 5 yeast strains will preform under the given conditions.  However, when I do use a new yeast stain I make sure to take a FG reading when signs of fermentation have slowed down or before I cool to transfer.  In the past I've used a plastic wine thief to take gravity readings, that was, before I contaminated it with oak barrel aged sour beer.    
« Last Edit: July 17, 2011, 03:39:20 PM by pyrite »
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Offline a10t2

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Re: How often do you check your gravity?
« Reply #4 on: July 17, 2011, 04:10:39 PM »
I take the first reading after visual indications indicate it's past high krausen, so 2-4 days depending on the yeast and gravity. Thereafter, every day, because I start to increase temperature once it's <5°P (1.020).

On the other hand, I've also let things sit for a month when I get busy. IME, if you don't under-pitch or introduce wild temperature variations, you shouldn't have a stalled fermentation. I've never had one.

And if you can't take a gravity reading without contaminating your beer, perhaps you should consider taking up knitting for a hobby!  ;)

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Offline SpanishCastleAle

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Re: How often do you check your gravity?
« Reply #5 on: July 18, 2011, 04:40:37 AM »
I measure gravity before fermentation and then catch a sample as I'm racking to the keg (usually at ~12 days but sometimes ~19 days for bigger beers).  I don't take gravity readings at all during the fermentation.  Even for lagers that I plan to D-rest I just eyeball it and raise the temp when I think it's about ready.  I always do an FFT so I know the limit of attenuation and it's almost always right there or just a point or so above it (often 2 points for lagers but it usually reduces another point or so as it lagers).

Offline oscarvan

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Re: How often do you check your gravity?
« Reply #6 on: July 18, 2011, 10:53:52 AM »
Twice..... Once right before pitching. If I get bubbles it's fermenting. I have finally learned some patience (malt hopper) and now for the average ale recipe just let buckets sit for three weeks, with the last few days at 40º. Then I keg and do the second reading, and I taste. Only if I am worried that something is wrong, and there usually isn't, will I do an intermediate reading.
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Offline maxieboy

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Re: How often do you check your gravity?
« Reply #7 on: July 18, 2011, 11:03:06 AM »
Before pitching and before racking or kegging.
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Offline richardt

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Re: How often do you check your gravity?
« Reply #8 on: July 18, 2011, 11:31:49 AM »
Checking with a hydrometer is critical if you're bottling.  You want to avoid bottle bombs.
It helps to know where your FG endpoint will be (hence the FFT)--this is the best way. 
A cruder way is to use the BeerSmith FG estimater (which I know some people on the forum hate).

Get your reading.  If they match up within a point or so, then you can use the tables that show how much sugar to add to the bottling bucket (or to the individual bottles) to get a certain number of volumes of CO2 in the beer.

If they don't, then the best thing is to wait a few more days.  Perhaps even raise the temps a few more degrees (get it warmer) and/or re-rouse the yeast gently (avoiding oxygenating the beer) with a swirling action.

I recommend planning ahead and giving yourself plenty of time to brew and bottle your entries, but, if you "have" to bottle today (let's say you're sending it off for a comp that's being held this weekend or next), then I figure that each gravity point adds about 0.6 volumes of CO2 to the 0.9 volumes of CO2 already in the fermented beer.  For example, if I had an APA with a SG of 1.018 that I knew would finish around 1.015, then I would add no priming sugar and go ahead and bottle it knowing that it should end up around 1.015 (and with 2.7 volumes of CO2), since the bottle stays warm during shipping and handling to the site, as well as during the organizing and labelling phases of the competition.  It gets chilled a few days prior to comp and you're good to go (and more importantly, you get no bottle bombs which may have occurred if you had added enough priming sugar to give 2.7 volumes + the 2.7 volumes from wort to yield 5.4 volumes of CO2).  Again, I would only do this shortcut if you know where your beer will end up.  I've been burned on this shortcut with a saison where the FG kept going into the single digits.  There were a few gushers.  I don't recommend this be a routine practice, of course.

Offline Al Equihua

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Re: How often do you check your gravity?
« Reply #9 on: July 18, 2011, 11:39:07 AM »
Well,  in my case i just wait two weeks in the primary and then just take the reading of the FG just before bottling. Sometimes when pick up in it is a little bubbling  :-[
usually it is fine for the final reading.
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Offline Malticulous

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Re: How often do you check your gravity?
« Reply #10 on: July 18, 2011, 02:03:05 PM »
I have been taking them all through the mash now I have a refratometer. I'll only take a hydrometer reading before I cold crash, keg or bottle. It's practically always at FG. I think the the FG is a more important aspect to the beer then the OG is.

Offline The Professor

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Re: How often do you check your gravity?
« Reply #11 on: July 18, 2011, 06:06:27 PM »
Two gravity checks for me:   once before the yeast is pitched and once when the beer goes from secondary into the keg.  Any more than that isn't necessary, (at least in my situation) since I only bottle from the keg.  And that's only after a cold aging period and the beer is already conditioned.

I usually know what to expect from the yeasts I use (especially my house strain) and have learned to just trust that as long as there's activity (visible activity in the first week or two) the yeasties are doing their job.   
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Offline uthristy

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Re: How often do you check your gravity?
« Reply #12 on: July 20, 2011, 06:13:07 AM »
Right before pitching yeast and at kegging, but if its a recipe/yeast I've brewed  many times I just check once.

Offline cenosillica

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Re: How often do you check your gravity?
« Reply #13 on: July 20, 2011, 08:28:59 AM »
For those of you who only check twice, is that just to calculate your ABV or are you checking to see if you have attenuated as expected for the type of yeast used. Calculating ABV is one good reason but I'm talking about checking more than twice to determine the best time to keg (or bottle if you swing that way).

If I have a yeast that attenuates at 60-70% then I'm looking for a wort with an OG of 1.100 to come down to 1.030-1.040. If I check for FG 2 weeks into a fermentation with a hydrometer and have a reading of 1.060 then I have a situation of under attenuation. There could be a variety of reasons behind this... mash efficiency, yeast health, fermentation temps etc....

This just recently happened where I expected 63-70% attenuation and only had 57%. I'm not sure I did the right thing but I sanitized a stirring spoon and roused the yeast cake slowly so as not to aerate the wort. I did this 11 days into fermentation after checking gravity 7 days into it and it not changing for 4 days. The other option I considered but did not do was to pitch more yeast or a champagne yeast.

What would you do if your gravity readings were >10% under-attenuated? Bottle and accept a sweeter beer? Leave it alone longer? Add more yeast? Stir yeast cake? Cross post in every forum?

I suppose all could be viable answers, I'm just looking for a consensus as to what most of you do in this situation.

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Re: How often do you check your gravity?
« Reply #14 on: July 20, 2011, 10:14:29 AM »
Your attenuation has less to do with your yeast than your recipe and procedure. You can use a super attenuative yeast but if your grain bill is heavy on the un-fermentables you will not get the same attenuation as you would if your recipe had no crystal and lots of cane sugar. The attenuation numbers on the yeast are a general guidline but not terribly accurate to the real world. So in a situation with under attenuation you could be looking at lots of causes

poor yeast health due to low aeration, underpitching, old yeast, ferm temp etc
poor fermentability of wort due to high mash temp, lots of old or dark extract, lots of crystal malts, poor conversion etc.

Speaking from experience if you have a beer that has stalled out at 1.040 and rousing the yeast didn't help it is unlikely that adding a new yeast will do anything. you are left with a few options

drink it as is
blend it with another, very attenuated beer
throw it out and start over
add bean-o  :P and then throw it out and start over.
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