Author Topic: Estimated FG Seems Odd  (Read 518 times)

Offline lbrennan41

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Estimated FG Seems Odd
« on: November 22, 2016, 06:59:05 PM »
I have only brewed with Marris Otter once before and I do not remember having any issues (either in Beer Smith OR with the beer) getting the beer down to 1.012 FG.  In fact almost all of my beers finish between 1.013 & 1.010.

This time, when formulating my recipe Beer Smith is telling me my estimated SG is 1.066 and estimated FG is 1.019. 

Mash at 152* for 60 minutes - Picnic Cooler Batch Sparge
10 lbs Marris Otter
1 lb 2-Row
1 lb Munich Malt
8 oz Aromatic Malt
4 oz Crystal 80
Wyeast 1768 (ESB)

My question - is there anything in this malt bill that seems like this beer should finish that high?  I think, like most of my other beers, it should finish around 1.012.  But Beer Smith is making me second guess myself.  I KNOW that the program is just estimating here but I have never had it estimate a finishing gravity that high on a beer I didn't want it to be.  Does Marris Otter convert less fermentable that 2-row?  I am thinking that I should proceed with assumption that the SG (1.066) is correct but the FG (1.019) is incorrect.  Seem Reasonable?

Thank All! - I don't post much but I lurk quite a bit.  I appreciate the help in advance.

Lucas
 

Offline stpug

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Re: Estimated FG Seems Odd
« Reply #1 on: November 22, 2016, 07:09:00 PM »
Over four batches, I saw 74-83% attenuation (AA) using single-infusion mashes ranging from 152F (83%AA) to 156F (74%AA) with Wyeast 1768.  If I were to use this strain again then I would use this as my rough guide.  Of course, everyone's system and process is different so you should take this with a few grains of salt.

You malt bill looks highly fermentable. I would not count on it to leave much residual sugars/sweetness on it's own (assuming a balanced IBU level).  You may be looking at around a 1.015 FG assuming a medium-high mash temperature with ~78%AA.

Offline EnkAMania

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Re: Estimated FG Seems Odd
« Reply #2 on: November 22, 2016, 07:14:39 PM »
Wyeast lists the minimum attenuation of 68% and maximum attenuation of 72%, so estimating 71.21% attenuation doesn't seem far fetched.
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Offline Phil_M

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Re: Estimated FG Seems Odd
« Reply #3 on: November 22, 2016, 07:28:12 PM »
FWIW, Wyeast also lists 3724 as having an 80% max, but myself (and I think some other on here) regularly get it to go well into the 90's.

Beersmith is even less accurate that the Wyeast specs.
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Offline HoosierBrew

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Re: Estimated FG Seems Odd
« Reply #4 on: November 22, 2016, 07:28:45 PM »
Yeah, looks like a pretty fermentable grist overall. Any problems with temp control this time? Flocculant English strains are prone to stalling if temp goes down during fermentation and benefit from raising temp after a few days to attenuate properly. Did you pitch the same amount of yeast as usual, I assume? Did you use a refractometer to measure FG? If so, there's a correction you need to use to get an accurate reading. Correct the reading for temp? Also, a 1.066 beer, while not huge, will generally finish higher than a 1.050 beer as well.

Finally, software estimates of attenuation and FG are utterly worthless. Your FG (and attenuation) depends on lots of factors - grist, mash temp, pH control, yeast health and quantity, etc. Though most of your beers finish ~ 1.012, lots of yeast/grist/mash temp combos will make beers that don't.
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Offline pete b

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Re: Estimated FG Seems Odd
« Reply #5 on: November 22, 2016, 07:55:29 PM »
I use Brewer's friend calculator and never used Beersmith but here's a WAG: does the program think you are throwing in a single pack when you usually use a starter? I assume that would change its calculation of FG.
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Offline lbrennan41

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Re: Estimated FG Seems Odd
« Reply #6 on: November 22, 2016, 08:06:52 PM »
Thanks for the responses.  I should have clarified, I have not brewed this yet.  I plan on brewing the day after Thanksgiving & was thrown off by the numbers Beer Smith gave me.  I get pretty good temp control this time of year and will be able to keep the beer around 64*-66* no problem.  Raising the temp after a few days sounds like it may be a good idea.  This is going to be an English style IPA coming in at an expected 60 IBU so maybe a little residual sweetness won't hurt it too much anyway.

I do use starters but from my recollection, starter vs. no starter doesn't affect Beer Smith's calculations that much.  I will need to double check that to make sure tho.

Offline denny

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Re: Estimated FG Seems Odd
« Reply #7 on: November 22, 2016, 08:09:20 PM »
Finally, software estimates of attenuation and FG are utterly worthless. Your FG (and attenuation) depends on lots of factors - grist, mash temp, pH control, yeast health and quantity, etc. Though most of your beers finish ~ 1.012, lots of yeast/grist/mash temp combos will make beers that don't.

THIS^^^^  Grist and process make a lot of difference in attenuation and software i doing nothing more than making a guess.  Yeast attenuation ratings are simply a way of comparing one yeast to another and do not necessarily reflect the attenuation you can expect.
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