Author Topic: FG Variance  (Read 2060 times)

Offline flbrewer

  • Brewmaster General
  • *******
  • Posts: 2161
    • View Profile
FG Variance
« on: January 30, 2015, 08:37:44 PM »
Just cold crashed my Regal Pale Ale and my FG is quite lower than the recipe called for. I'm sure I used the correct amount of grain...what else could cause this? I didn't really want a higher ABV, but I guess there are worse things!

Recipe- OG- 1.056, FG- 1.014 (5.5% ABV)

My Brew- OG- 1.057, FG- 1.008 (6.4% ABV)*

*This is an 85% apparent attenuation.

Offline Joe Sr.

  • Official Poobah of No Life.
  • *
  • Posts: 4383
  • Chicago - NORTH SIDE
    • View Profile
Re: FG Variance
« Reply #1 on: January 30, 2015, 08:41:37 PM »
I'm sure I used the correct amount of grain...what else could cause this?

Mash temp and mash time are the first things that come to mind. I'm sure there are other variables. 

Final gravities in recipes are an estimate.
It's all in the reflexes. - Jack Burton

Offline HoosierBrew

  • Global Moderator
  • I must live here
  • *****
  • Posts: 13030
  • Indianapolis,IN
    • View Profile
Re: FG Variance
« Reply #2 on: January 30, 2015, 08:43:23 PM »
You used a hydrometer and corrected for temperature ?  Remember, FG estimates from recipes or software are just that - estimates.  Several factors figure into your FG - yeast strain/quantity/health, mash temp, your grain bill.
Jon H.

Offline denny

  • Administrator
  • Retired with too much time on my hands
  • *****
  • Posts: 19938
  • Noti OR [1991.4, 287.6deg] AR
    • View Profile
    • Dennybrew
Re: FG Variance
« Reply #3 on: January 30, 2015, 08:54:53 PM »
Just cold crashed my Regal Pale Ale and my FG is quite lower than the recipe called for. I'm sure I used the correct amount of grain...what else could cause this? I didn't really want a higher ABV, but I guess there are worse things!

Recipe- OG- 1.056, FG- 1.014 (5.5% ABV)

My Brew- OG- 1.057, FG- 1.008 (6.4% ABV)*

*This is an 85% apparent attenuation.

I say this over and over....just ignore it when a recipe tries to predict FG.  It's so inexact as to be worthless.  If the recipe is correct, it's more luck than anything.
Life begins at 60.....1.060, that is!

www.dennybrew.com

The best, sharpest, funniest, weirdest and most knowledgable minds in home brewing contribute on the AHA forum. - Alewyfe

"The whole problem with the world is that fools and fanatics are always so certain of themselves, and wiser people so full of doubts." - Bertrand Russell

Offline flbrewer

  • Brewmaster General
  • *******
  • Posts: 2161
    • View Profile
Re: FG Variance
« Reply #4 on: January 30, 2015, 08:55:22 PM »
You used a hydrometer and corrected for temperature ?

Yup

Offline HoosierBrew

  • Global Moderator
  • I must live here
  • *****
  • Posts: 13030
  • Indianapolis,IN
    • View Profile
Re: FG Variance
« Reply #5 on: January 30, 2015, 08:56:21 PM »
You used a hydrometer and corrected for temperature ?

Yup

Then what Denny said. FG estimates are worthless.
Jon H.

Offline Jimmy K

  • Official Poobah of No Life.
  • *
  • Posts: 3646
  • Delaware
    • View Profile
Re: FG Variance
« Reply #6 on: January 30, 2015, 09:11:13 PM »
My first mash thermometer was a basic kitchen digital thermometer. I checked it one day against a better thermometer and it was almost 10 degrees low. So when I thought I was at 155 I was really around 145. That would dry your beer out!
Delmarva United Homebrewers - President by inverse coup - former president ousted himself.
AHA Member since 2006
BJCP Certified: B0958

Offline Wort-H.O.G.

  • Official Poobah of No Life.
  • *
  • Posts: 4439
  • Play Nice
    • View Profile
    • Harvey's Brewhaus
Re: FG Variance
« Reply #7 on: January 30, 2015, 09:13:49 PM »
might be a little more dry than you like and little less mouth feel.....but its beer and all things considered, that's at worst a small challenge to tackle and overcome in next batch.
Ken- Chagrin Falls, OH
CPT, U.S.Army
https://www.facebook.com/pages/Harveys-Brewhaus/405092862905115

http://braukaiser.com/wiki/index.php?title=The_Science_of_Mashing

Serving:        In Process:
Vienna IPA          O'Fest
Dort
Mead                 
Cider                         
Ger'merican Blonde
Amber Ale
Next:
Ger Pils
O'Fest

Offline flbrewer

  • Brewmaster General
  • *******
  • Posts: 2161
    • View Profile
Re: FG Variance
« Reply #8 on: January 30, 2015, 09:15:19 PM »

My first mash thermometer was a basic kitchen digital thermometer. I checked it one day against a better thermometer and it was almost 10 degrees low. So when I thought I was at 155 I was really around 145. That would dry your beer out!
I pretty confident in my Thermapen, something to think about though.

Offline denny

  • Administrator
  • Retired with too much time on my hands
  • *****
  • Posts: 19938
  • Noti OR [1991.4, 287.6deg] AR
    • View Profile
    • Dennybrew
Re: FG Variance
« Reply #9 on: January 30, 2015, 09:22:11 PM »

My first mash thermometer was a basic kitchen digital thermometer. I checked it one day against a better thermometer and it was almost 10 degrees low. So when I thought I was at 155 I was really around 145. That would dry your beer out!
I pretty confident in my Thermapen, something to think about though.

It could be something as basic as differences in the malt you used vs. the "typical" malt used in the FG prediction.  Seriously, just ignore that in the future.
Life begins at 60.....1.060, that is!

www.dennybrew.com

The best, sharpest, funniest, weirdest and most knowledgable minds in home brewing contribute on the AHA forum. - Alewyfe

"The whole problem with the world is that fools and fanatics are always so certain of themselves, and wiser people so full of doubts." - Bertrand Russell

Offline flbrewer

  • Brewmaster General
  • *******
  • Posts: 2161
    • View Profile
Re: FG Variance
« Reply #10 on: January 30, 2015, 09:26:08 PM »
There was the whole "Caravienne" misunderstanding at my LHBS. It was only 5 ounces though, apparently what I got was something closer to a crystal grain.


Offline Wort-H.O.G.

  • Official Poobah of No Life.
  • *
  • Posts: 4439
  • Play Nice
    • View Profile
    • Harvey's Brewhaus
Re: FG Variance
« Reply #11 on: January 30, 2015, 09:34:14 PM »
mash temp-what was it?
Ken- Chagrin Falls, OH
CPT, U.S.Army
https://www.facebook.com/pages/Harveys-Brewhaus/405092862905115

http://braukaiser.com/wiki/index.php?title=The_Science_of_Mashing

Serving:        In Process:
Vienna IPA          O'Fest
Dort
Mead                 
Cider                         
Ger'merican Blonde
Amber Ale
Next:
Ger Pils
O'Fest

Offline flbrewer

  • Brewmaster General
  • *******
  • Posts: 2161
    • View Profile
Re: FG Variance
« Reply #12 on: January 30, 2015, 10:45:42 PM »
mash temp-what was it?

153. Recipe called for 154. Could it be a water volume issue?

Offline brewday

  • Brewer
  • ****
  • Posts: 453
  • Chicago
    • View Profile
Re: FG Variance
« Reply #13 on: January 30, 2015, 10:56:55 PM »
mash temp-what was it?

153. Recipe called for 154. Could it be a water volume issue?

If you added water after you measured post-boil gravity, then maybe.  1.008 is low, but not crazy low.  Have you calibrated your hydrometer in water?  Mine reads .04 pts high, so I always know to compensate for that.
Jon Weaver

Offline flbrewer

  • Brewmaster General
  • *******
  • Posts: 2161
    • View Profile
Re: FG Variance
« Reply #14 on: January 30, 2015, 10:57:35 PM »
mash temp-what was it?

153. Recipe called for 154. Could it be a water volume issue?

If you added water after you measured post-boil gravity, then maybe.  1.008 is low, but not crazy low.  Have you calibrated your hydrometer in water?  Mine reads .04 pts high, so I always know to compensate for that.

That's an idea...let me check it.