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General Category => Yeast and Fermentation => Topic started by: cenosillica on July 17, 2011, 09:00:17 PM

Title: How often do you check your gravity?
Post by: cenosillica on July 17, 2011, 09:00:17 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?
Title: Re: How often do you check your gravity?
Post by: denny on July 17, 2011, 09:08:08 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!  ;)
Title: Re: How often do you check your gravity?
Post by: Thirsty_Monk on July 17, 2011, 09:36:23 PM
I am taking reading every day after pitching just to make sure I have fermentation going.
Title: Re: How often do you check your gravity?
Post by: pyrite on July 17, 2011, 10:37:33 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.    
Title: Re: How often do you check your gravity?
Post by: a10t2 on July 17, 2011, 11:10:39 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!  ;)

That still makes me laugh every time.
Title: Re: How often do you check your gravity?
Post by: SpanishCastleAle on July 18, 2011, 11:40:37 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).
Title: Re: How often do you check your gravity?
Post by: oscarvan on July 18, 2011, 05:53:52 PM
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.
Title: Re: How often do you check your gravity?
Post by: maxieboy on July 18, 2011, 06:03:06 PM
Before pitching and before racking or kegging.
Title: Re: How often do you check your gravity?
Post by: richardt on July 18, 2011, 06:31:49 PM
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.
Title: Re: How often do you check your gravity?
Post by: Al Equihua on July 18, 2011, 06:39:07 PM
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.
Title: Re: How often do you check your gravity?
Post by: Malticulous on July 18, 2011, 09:03:05 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.
Title: Re: How often do you check your gravity?
Post by: The Professor on July 19, 2011, 01:06:27 AM
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.   
Title: Re: How often do you check your gravity?
Post by: uthristy on July 20, 2011, 01:13:07 PM
Right before pitching yeast and at kegging, but if its a recipe/yeast I've brewed  many times I just check once.
Title: Re: How often do you check your gravity?
Post by: cenosillica on July 20, 2011, 03:28:59 PM
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.
Title: Re: How often do you check your gravity?
Post by: morticaixavier on July 20, 2011, 05:14:29 PM
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.
Title: Re: How often do you check your gravity?
Post by: jeffy on July 20, 2011, 05:26:16 PM
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.

You forgot add brett and wait.  That's what I did with the one I had last year.  I missed my strike temp way too high and probably destroyed all the enzymes in the time it took to cool the mash.  Strong Scotch ale that finished at 1.040.  Pitched brett b and had a pelicle soon after.
Title: Re: How often do you check your gravity?
Post by: morticaixavier on July 20, 2011, 05:39:10 PM
good call, another option.
Title: Re: How often do you check your gravity?
Post by: Joe Sr. on July 20, 2011, 08:53:16 PM
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.

Rousing the yeast was a good idea.  You can also try to warm up the fermenter at the same time.

I've only encountered this with Belgian Saison yeast, which I find to be a real PITA to use but will probably use again, and have found that patience, lots and lots of patience, is required.  I have lots of overcarbed bottles of saison due to not being patient enough after rousing the yeast, warming the carboy and waiting.  The gravity dropped a little bit, but it seemed to be stalled.  Apparently not.

Luckily, I used champagne bottles so I have not had any explosions.  But the corks come flying out.  Which can be dangerous in itself.
Title: Re: How often do you check your gravity?
Post by: Will's Swill on July 20, 2011, 11:54:55 PM
I've had two stall out recently, neither of which responded to rousing the yeast.  One of them I tried raising the temp up pretty high without getting any additional gravity drop.  In both cases I pitched a small starter at high krausen and got the FG down close to where I wanted it.  YMMV.
Title: Re: How often do you check your gravity?
Post by: SpanishCastleAle on July 21, 2011, 11:50:26 AM
This is exactly why I only check it twice and the second one is caught as I'm racking to the keg.  The rare stuck fermentations I've had did not respond to rousing, raising the temp, adding yeast energizer (usually a combination of all three).  Since the yeast were obviously not up to the task I figure it's best to get it off the stressed yeast.  So ime, usually once the original pitch of yeast has stopped, it's done, it ain't going any further and racking is the next step.

As for what to do when a fermentation is stuck, ime the best methods to fix it are (in order):
Rack it onto the yeast cake of a 'good' fermentation (or add the cake to the keg).  Do not aerate.
Add properly hydrated dry yeast.  Dry yeast doesn't need O2 so you don't have to worry about the fact that you don't aerate (which you definitely don't want to do at that point).
Krausen it.

After any of these had run their course I would then do closed keg-to-keg transfer.
Title: Re: How often do you check your gravity?
Post by: bluesman on July 21, 2011, 12:59:47 PM
More than often twice. Before fermentation (OG) and just before racking (FG). I like to use the airlock as an indicator of the fermentation process, so when the airlock activity subsides (typically 1-2 weeks for ales/2-3 weeks for lagers), I'll take a gravity reading and proceed to racking if it's wher I think it should be based on the recipe and the yeast. It comes with experience. The more beer you brew, the better your instincts.
Title: Re: How often do you check your gravity?
Post by: beersk on July 21, 2011, 02:03:36 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!  ;)
Man, you don't give knitting enough credit!  That sh*t's hard!

I take a reading when the krausen falls and before I keg.
Title: Re: How often do you check your gravity?
Post by: denny on July 21, 2011, 03:22:11 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!  ;)
Man, you don't give knitting enough credit!  That sh*t's hard!

I'm all too aware of that...I learned to knit when I was in 2nd grade.  I remember my Dad's horror when some of my friends came over to get me to go out and play football with them and I told then I'd be there as soon as I finished the row I was on!
Title: Re: How often do you check your gravity?
Post by: dbeechum on July 21, 2011, 03:56:16 PM
Your momma had you done up in one of those boy's dresses didn't she. Don't fret! Those were popular when you were born around the turn of the century!
Title: Re: How often do you check your gravity?
Post by: tschmidlin on July 21, 2011, 04:54:26 PM
Your momma had you done up in one of those boy's dresses didn't she. Don't fret! Those were popular when you were born around the turn of the century!
Denny's baby picture is a daguerreotype. ;) ;D
Title: Re: How often do you check your gravity?
Post by: denny on July 21, 2011, 04:56:51 PM
Your momma had you done up in one of those boy's dresses didn't she. Don't fret! Those were popular when you were born around the turn of the century!
Denny's baby picture is a daguerreotype. ;) ;D

Wrong...it's a cave painting!
Title: Re: How often do you check your gravity?
Post by: cenosillica on July 21, 2011, 05:01:05 PM
I ahh... don't know what to say... Perhaps I'm getting more information than I bargained for?
Title: Re: How often do you check your gravity?
Post by: oscarvan on July 22, 2011, 03:14:48 AM
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!  ;)
Man, you don't give knitting enough credit!  That sh*t's hard!

I'm all too aware of that...I learned to knit when I was in 2nd grade.  I remember my Dad's horror when some of my friends came over to get me to go out and play football with them and I told then I'd be there as soon as I finished the row I was on!

Montessori School? Same here..... knitting, embroidery, crochet..... To all the testosterone knights..... buzz off. I can still pull out a needle and thread and make happen what I need to happen. And as far as a bunch of guys chasing a ball.....get your own ball. OK, back to "carbonation checks"..... ;D
Title: Re: How often do you check your gravity?
Post by: pyrite on July 22, 2011, 05:51:38 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.

You forgot add brett and wait.  That's what I did with the one I had last year.  I missed my strike temp way too high and probably destroyed all the enzymes in the time it took to cool the mash.  Strong Scotch ale that finished at 1.040.  Pitched brett b and had a pelicle soon after.

I had a similar issue when I over shot my mash temps when I was tinkering with decoction mashing.

I brewed 5gallons of a dopple bock @ 7% a month ago, and the FG read 1.022 which is a bit high for my taste.  I first thought about adding some brett but then thought it wouldn't fit the style.  If it were a Scotch ale or some other ale I might give it a go but it's a lager.  So instead, I'm going to blend it with a lager fermented with the same German Bock Lager yeast that reached a FG of 1.012.  I think this will fix the problem, by just waiting another month until the next lager batch is done and then I'll  blend the two batches.  
Title: Re: How often do you check your gravity?
Post by: denny on July 22, 2011, 03:38:55 PM

Montessori School? Same here..... knitting, embroidery, crochet..... To all the testosterone knights..... buzz off. I can still pull out a needle and thread and make happen what I need to happen. And as far as a bunch of guys chasing a ball.....get your own ball. OK, back to "carbonation checks"..... ;D

I don't know if Montessori had even thought of a school when I was in school in IA in the 50s/60s.  There sure as heck weren't any around where I lived at any rate,
Title: Re: How often do you check your gravity?
Post by: chumley on July 22, 2011, 08:08:00 PM
To answer the original question, once.  When I dump the wort into the primary, I check to see how close my OG is to what I am aiming for.

I am so slow anymore to rack to a keg, I rarely bother to check the FG.  Usually its lower than what I expect it to be. I do like to check the Belgian strains, though, as they seem to be more of a crapshoot where they end at.
Title: Re: How often do you check your gravity?
Post by: narcout on July 22, 2011, 10:29:47 PM
I've only encountered this with Belgian Saison yeast, which I find to be a real PITA to use but will probably use again, and have found that patience, lots and lots of patience, is required.

Do yourself a favor and try the 3711 Wyeast French Saison strain.  It ferments quickly, predictably, and fully in the upper 60's/low 70's.  It also has a great flavor profile and has become my go to Saison yeast.
Title: Re: How often do you check your gravity?
Post by: oscarvan on July 24, 2011, 02:55:07 PM

Montessori School? Same here..... knitting, embroidery, crochet..... To all the testosterone knights..... buzz off. I can still pull out a needle and thread and make happen what I need to happen. And as far as a bunch of guys chasing a ball.....get your own ball. OK, back to "carbonation checks"..... ;D

I don't know if Montessori had even thought of a school when I was in school in IA in the 50s/60s.  There sure as heck weren't any around where I lived at any rate,

Maria Montessori started her first school in Italy in 1907....... There was one in my hometown in Holland as early as the 30's which my mother attended in the 40's. I sat in the same class rooms in the 60's.... The Montessori story is really a remarkable one. Unfortunately the proponents in this country are less pragmatic and come from the far left side of the aisle and proud of it. This has alienated a lot of people and placed a stigma on the name......really a shame.

Read more here:

http://en.wikipedia.org/wiki/Maria_Montessori

Oh, and excuse the thread drift........