High altitude ABV challenges at 6500’

[43North]

I can only hit 50% of my ABV I’m a newbie and have brewed about four batches. 1-lager, 1- ale all grain, 2-stouts participle extract.

1. I’ve always hit or exceeded my post-boil gravity.
2. I don’t use secondary fermentation I just leave it in the fermenter for twice as long.
3. I have a temperature controlled fermentation chest using Inkbird.

• Can yeast have a challenge at altitude?
• can my post-gravity be so high I’m killing my yeast?
• Is my yeast running out of mojo before they get all the sugar converted?

I’m really struggling.

On the positive side, I got some really good tasting 2-3 % ABV beer

 

[hopjuice_71]

Are you measuring your final gravity with a hydrometer or refractometer? Refractometer readings need to be corrected when alcohol is present. This is about the only reasonable explanation I have for falling so short on your FG.

 

[AZCoolerBrewer]

Alternatively if a person threw their hydrometer into really hot wort, you could get a high OG reading if you didn’t correct for temp.

 

[43North]

Are you measuring your final gravity with a hydrometer or refractometer? Refractometer readings need to be corrected when alcohol is present. This is about the only reasonable explanation I have for falling so short on your FG.

I’m using a refractor

 

[43North]

Alternatively if a person threw their hydrometer into really hot wort, you could get a high OG reading if you didn’t correct for temp.

All readings at 68 to 70°

 

[Deric]

Are you correcting the final gravity readings for the presence of alcohol?

Helpful calculator here.....
https://www.brewersfriend.com/refractometer-calculator/

 

[43North]

I wasn’t aware that refractor needed adjustments! I’ll look into this.

I’ve read a few articles in the last 30 min and It looks like it might add 1.5% to my ABV so now I’m at about 3.2% on a beer that should be 6%. I’m afraid my yeast pop is not high enough due to elevation?

 

[hopjuice_71]

I wasn’t aware that refractor needed adjustments! I’ll look into this.

I’ve read a few articles in the last 30 min and It looks like it might add 1.5% to my ABV so now I’m at about 3.2% on a beer that should be 6%. I’m afraid my yeast pop is not high enough due to elevation?

There are calculators, not just adding 1.5%. This, I think, is a popular one: Refractometer Calculator - Brewer's Friend. Oops, just saw that Deric linked this....

Edit: for example, if your OG Brix reading was 15 and your FG Brix reading was ~9 you might calculate an ABV of ~3.5%, whereas with a proper correction it would be about 6%.

 

[hopjuice_71]

Alternatively if a person threw their hydrometer into really hot wort, you could get a high OG reading if you didn’t correct for temp.

Isn't it the other way around? Hot wort + hydrometer = low reading? Heat lowers the viscosity of sugar solutions.....

 

[Deric]

I wasn’t aware that refractor needed adjustments! I’ll look into this.

I’ve read a few articles in the last 30 min and It looks like it might add 1.5% to my ABV so now I’m at about 3.2% on a beer that should be 6%. I’m afraid my yeast pop is not high enough due to elevation?

What were you're OG (original gravity) and FG (final gravity) readings on your refractometer?

 

[Wayne1]

Altitude will not affect ABV. I had no problem making 9% ABV Imperial Stouts in Vail, CO at 8500 feet.

I am at 5500 feet in surburban Denver, CO and can brew any ABV I choose.

What I am seeing here is operator error.

Use the correct tools for the job and learn how to use them correctly.

Hydrometer for OG and FG.

 

[Brewer Mike]

+1 with Wayne1. It's not the yeast (assuming you use the common variants available at homebrew stores). I brew at 5700' and don't have issues with ABV.
Are you fermenting in the yeast's prescribed temperature range. Oxygenating the wort?

 

[DBhomebrew]

Hey, @43North, how'd the calculator work out for you?

 

[hotbeer]

Refractors are probably great for quick readings to just compare relativity to a previous sample. But for OG and FG I'd use and only trust a real hydrometer. They only cost $6 - $12. Many including their own jar or flask to put the sample in.

Apologies for the PSA.

Once the corrections are done to your readings, maybe we can suggest some things. But probably going to need more info about how you ferment and control conditions.

Have you ever done a iodine test while mashing?

 

[DBhomebrew]

Not so much a PSA as a public airing of opinion. Nothing wrong with that of course.

We don't know there's a problem until OP returns with calculator results.

 

[hotbeer]

PSA

Pesonal Supposition Advice !

 

[AZCoolerBrewer]

Isn't it the other way around? Hot wort + hydrometer = low reading? Heat lowers the viscosity of sugar solutions.....

Yes, so the OP would use his low OG to calculate ABV, with an FG that would be higher due to the higher actual starting gravity. Say your wort was 1.069 and you measured 1.050 in hot wort, then it ferments down to 1.018. You would think that you had a 4.2% when you really had a 6.7%

Another possibility is using a measurement before the boil, you’d see a similar situation.

 

[hopjuice_71]

Yes, so the OP would use his low OG to calculate ABV, with an FG that would be higher due to the higher actual starting gravity. Say your wort was 1.069 and you measured 1.050 in hot wort, then it ferments down to 1.018. You would think that you had a 4.2% when you really had a 6.7%

Another possibility is using a measurement before the boil, you’d see a similar situation.

Right, now I understand what you are saying, and that could be another scenario....turns out he used a refractometer though.

 

[hotbeer]

And how are you getting your ABV numbers? This is a common formula.... ABV = (OG - FG) * 131.25

Or use the calculator on Brewer's Friend. Alcohol By Volume ABV Calculator | Brewer's Friend

Sharing your readings you took with the refractometer might let others double check your results.

 

[AZ Maverick]

I'm also suspecting that that it is a refractometer reading error.
I only use my refractometer anymore when I brew, I haven't used my hydrometer in years.
I did calibrate my refractometer with my hydrometer and my results are within reasonable error results.
My refractometer also tracks with my Tilt hydrometers during fermentation - I do use the Brewers Friend Refractometer Calculator.
I brew at 5400' above sea level and I have no problems with 10% abv brews, measured with either a hydrometer, refractometer, or Tilt.

 

[43North]

Thanks to all of you who have been contributing to this thread since July.