What is causing my FG to be 1039?

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Belgian Samurai

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Hi,

Why is my FG appearing as if it's going to finish so high at 1.039? (Day 2 of 1.039.) The OG was 1.073 (calibrated refractometer @ 20⁰C). The beer was delicious last time I brewed it. Anything I should consider on changing?

Ingredients
0.43 kg White Wheat Malt
Mash (10.3%) -4.7 EBC

0.43 kg - Pale Malt (2 Row) US Mash (10.3%) -3.9 EBC

14.0 g-Hallertauer Mittelfrueh
Boll 60 min (7.3 IBUS)

14.0 g Hallertauer Mittelfrueh
Boil 60 min (5.7 IBUs)

2.35 kg - Wheat Dry Extract
Late extract addition: 20 min (57.2%) -15.8 EBC

170.00 g - Orange zest
Boil 5.0 min

170.00 g - Coriander Seed
Boil 5.0 min

0.91 kg - Cane (granulated) Sugar
(Post gravity reading; pre-yeast pitching)

1 pkg - SafBrew Ale
DCL/Fermentis #S-33

Topped off to 18.93 liters / 5 gallons of water.
 
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DonT

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If your OG is 1.037, your FG can't be higher. Also, get a hydrometer. Refractometers aren't accurate when alcohol is present.
I'm assuming you transposed those measurements... If so, give it a good swirl and RDWHAHB
 
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Belgian Samurai

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If your OG is 1.037, your FG can't be higher. Also, get a hydrometer. Refractometers aren't accurate when alcohol is present.
I'm assuming you transposed those measurements... If so, give it a good swirl and RDWHAHB
You are right, I did invert those numbers. I have since corrected it to 1.073. I thought a refractometer wouldn't be accurate when carbonation was present. So I made sure the beer was flat before testing it.
 

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The refractometer should be able to deal with carbonated beer pretty well, actually. And it's true that refractive index alone won't give you a sugar concentration measurement if there's also alcohol present. However, a specific gravity reading with a hydrometer also doesn't give you a sugar concentration measurement if there's alcohol present.
 
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Belgian Samurai

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The refractometer should be able to deal with carbonated beer pretty well, actually.
Interesting!! That got me to wondering, so I just took another gravity reading and here were the different variables:

First reading an hour ago:
Flat beer @ 21⁰c/70⁰f: 1.039

New reading just now:
Carbonated (2.5vol CO2) @ 27⁰c/80⁰f: 1.039

Fascinating!
(BTW, I'm pressure fermenting this in a keg.)
 
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No estimated FG in the recipe? FWIW, with DME & S-33, don't expect 80% attenuation.
 
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TheMadKing

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the reading is falsely high because you're using a refractometer in the presence of alcohol. That's the only issue going on. A calculator will work if you want to determine your wort correction factor


Just measure with a hydrometer to get an accurate measurement of apparent attenuation.
 

DBhomebrew

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OP hasn't yet confirmed whether or not they use a refractometer calculator to arrive at a FG of 1.039. Assuming they have not...

Figuring observed Brix readings as 18.5 and 10.5 (w/ a 1.04 WCF), the Brewer's Friend calculator gives an actual FG of 1.022.

NB: This doesn't figure in the post gravity reading sugar addition. OG should include that.
 

DBhomebrew

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post #3.

It was the 2nd thought of a two thought paragraph. ;)

I don't see it there either.

You are right, I did invert those numbers. I have since corrected it to 1.073. I thought a refractometer wouldn't be accurate when carbonation was present. So I made sure the beer was flat before testing it.

1 - OG corrected to be 1.073, not 1.037

2 - Refractometers and carbonation

Mention of refractometer calculator? Negative
 

VikeMan

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@Belgian Samurai did you, or did you not, use a refractometer calculator, and if so, which one? If you did not:

well-theres-your-4189237456.jpg
 

MicroMickey

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Whether you used a refractometer or not. Whether you transposed the numbers or not. Did you oxygenate the wort properly when you pitched the yeast? That, in my mind, is the central question. High terminal gravities can be easily explained by lack of nutrients, yeast in poor condition, and / or lack of proper aeration.
 
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Belgian Samurai

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@Belgian Samurai did you, or did you not, use a refractometer calculator, and if so, which one? If you did not:
I did not. I will look into how to use them. I've just began using the BeerSmith 3 app.
Whether you used a refractometer or not. Whether you transposed the numbers or not. Did you oxygenate the wort properly when you pitched the yeast? That, in my mind, is the central question. High terminal gravities can be easily explained by lack of nutrients, yeast in poor condition, and / or lack of proper aeration.
Yep, sure did. I shook the heck out of that keg.
 

DBhomebrew

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Whether you used a refractometer or not. Whether you transposed the numbers or not. Did you oxygenate the wort properly when you pitched the yeast? That, in my mind, is the central question. High terminal gravities can be easily explained by lack of nutrients, yeast in poor condition, and / or lack of proper aeration.

Why bother troubleshooting a high final gravity without first checking to be sure your measurement is correct?

Case in point, OP just confirmed that their 1.039 is thoroughly erroneous.
 
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Belgian Samurai

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Be sure to factor in your post-measurememt sugar addition as part of the OG.
I have a question about how the cane sugar should be added. I added it after I took the original gravity reading, THEN added the sugar and pitched the yeast. I didn't do a whirlpool, but that is the only place to add it to the recipe. Was that acceptable? How would you have added it in the app? (I'm still learning the app.)

Screenshot_20221004-101721.png Screenshot_20221004-101710.png
 
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High terminal gravities can be easily explained by lack of nutrients, yeast in poor condition, and / or lack of proper aeration.

As mentioned earlier ...

No estimated FG in the recipe? FWIW, with DME & S-33, don't expect 80% attenuation.

... and with some additional information from Fermentis Tips & Tricks (p 43) ...

1664896837959.png
eta: there are a number of dry yeast strings (S-33, Windsor, London ESB) that behave this way. For me, they don't work well with DME. I get good results with these strains when I occasionally brew styles with a 'low & long' full volume mash.
 

DBhomebrew

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I have a question about how the cane sugar should be added. I added it after I took the original gravity reading, THEN added the sugar and pitched the yeast. I didn't do a whirlpool, but that is the only place to add it to the recipe. Was that acceptable? How would you have added it in the app? (I'm still learning the app.)

View attachment 782802 View attachment 782803

I don't know about the software. But in regards to the physical beer and refractometer in front of you...

You've measured 1.073, then added 0.91kg (2lb) of sugar. Sugar adds 46 gravity points per pound. You added 92 points across 5 gallons.

73+(92/5)
91.4

Your actual OG is roughly 1.091, or ~23Brix.

With  that in the calculator, you're looking at a FG of 1.011

@MicroMickey, should we still troubleshoot aeration and nutrient levels?
 

VikeMan

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I couldn't help but notice that the pre-sugar addition reported OG of 1.073 seemed awfully high for the grain bill, even in my non-native-metric-estimating brain. So I ran some numbers.

18.93 liters
0.43 kg White Wheat Malt
0.43 kg - Pale Malt (2 Row) US
2.35 kg - Wheat Dry Extract

Even at 100% mash efficiency for the malts (which of course is impossible), this would only come out to about 1.060. At a more reasonable 75% mash efficiency, we're looking at about 1.056.

So...something is off about the OG reading, or the stated recipe, or my reading comprehension. My guess would be that the reading was taken from a sample that hadn't been thoroughly mixed with the top off water.
 

bike2brew

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Likewise I checked with the refractomer calculator on Brewer's Friend to come up w/ these numbers using his 1.073 OG. His FG (1.037) converted with alcohol present was 1.017 w/ approx 7.39% ABV and ~ 76% attenuation. So overall not bad @ 2 days fermentation. This seems awfully quick for me given my experience w/ a Tripel last March. Wonder what his fermentation temperature was? I have since gone to using the Tilt for monitoring and to get the other relevant temperature data.
 

DBhomebrew

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I couldn't help but notice that the pre-sugar addition reported OG of 1.073 seemed awfully high for the grain bill, even in my non-native-metric-estimating brain. So I ran some numbers.

18.93 liters
0.43 kg White Wheat Malt
0.43 kg - Pale Malt (2 Row) US
2.35 kg - Wheat Dry Extract

Even at 100% mash efficiency for the malts (which of course is impossible), this would only come out to about 1.060. At a more reasonable 75% mash efficiency, we're looking at about 1.056.

So...something is off about the OG reading, or the stated recipe, or my reading comprehension. My guess would be that the reading was taken from a sample that hadn't been thoroughly mixed with the top off water.

And with the sugar, that puts it at ~1.074. Back to a FG of ~1.022 with an attenuation of ~70%.
 
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Belgian Samurai

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I couldn't help but notice that the pre-sugar addition reported OG of 1.073 seemed awfully high for the grain bill, even in my non-native-metric-estimating brain. So I ran some numbers.

18.93 liters
0.43 kg White Wheat Malt
0.43 kg - Pale Malt (2 Row) US
2.35 kg - Wheat Dry Extract

Even at 100% mash efficiency for the malts (which of course is impossible), this would only come out to about 1.060. At a more reasonable 75% mash efficiency, we're looking at about 1.056.

So...something is off about the OG reading, or the stated recipe, or my reading comprehension. My guess would be that the reading was taken from a sample that hadn't been thoroughly mixed with the top off water.
Oh, man, I cannot remember if I took that OG before the top-off water or not. It's not mentioned in my notes.
 

VikeMan

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Oh, man, I cannot remember if I took that OG before the top-off water or not. It's not mentioned in my notes.

Well, even if you take it after topping off (which you should), you have to make sure it's very thoroughly mixed. Not mixing thoroughly after topping off is probably the most common gravity measurement mistake with partial boil batches.

Fortunately, most of your gravity came from extract, so mash efficiency has less effect than it typically does, and the expected gravity is more predictable. I would go ahead and assume an OG of 1.056 (pre-sugar) and you won't be far off.
 
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Belgian Samurai

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This week, I will study/learn about brix and calculators. Thanks, everyone! ✌️

Likewise I checked with the refractomer calculator on Brewer's Friend to come up w/ these numbers using his 1.073 OG. His FG (1.037) converted with alcohol present was 1.017 w/ approx 7.39% ABV and ~ 76% attenuation. So overall not bad @ 2 days fermentation. This seems awfully quick for me given my experience w/ a Tripel last March. Wonder what his fermentation temperature was? I have since gone to using the Tilt for monitoring and to get the other relevant temperature data.
I was pressure fermenting in a keg with temps in the 20Cs/70Fs. For that, I did use a CO2/PSI calculator.
 

bike2brew

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I converted his base grains to extract and totaled w/ the WDE to get 4kg DME. Used in a 19 liter batch, the est OG is 1.079 and w/ 75% attenuation the predicted FG is 1.022. So again, coming into the ballpark. I suspect as everyone else has pointed out previously the OP has just not accounted for the alcohol presence in his readings.

I do have plans for another Tripel soon and will monitor the fermentation progress better next time.

I love these calculators and the telemetry for reducing the guess work. However, I have other very capable brewing friends that still enjoy a black magic approach.
 

hotbeer

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Most everything for measuring efficiency for mash and beer fermentation revolves around specific gravity. Refractometers require more effort to get a approximation of specific gravity. And as evidenced in many threads here can cause quite a long and confusing discussion.

So just get a hydrometer and use it to double check your results with the refractometer. Then you'll know quickly if you are calculating correction factors incorrectly. After you know you are getting the same numbers, you can exclusively use your refractometer.

Hydrometers are very inexpensive.
 

VikeMan

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I converted his base grains to extract and totaled w/ the WDE to get 4kg DME. Used in a 19 liter batch, the est OG is 1.079 and w/ 75% attenuation the predicted FG is 1.022.

I assume you included the sugar in this calculation, because otherwise:

Roughly speaking, a kg of malt at 75% efficiency = ~ 0.6 kg of DME (or WME).

0.86 kg Malt + 2.35 kg Extract =
(0.86 kg Malt x (0.6 Extract/Malt)) + 2.35 kg Extract =
= ~2.9 kg Extract
 

bike2brew

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I assume you included the sugar in this calculation, because otherwise:

Roughly speaking, a kg of malt at 75% efficiency = ~ 0.6 kg of DME (or WME).

0.86 kg Malt + 2.35 kg Extract =
(0.86 kg Malt x (0.6 Extract/Malt)) + 2.35 kg Extract =
= ~2.9 kg Extract
 
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