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Old 02-01-2013, 07:57 PM   #1
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Default Refractometer post fermentation correction formula

Does anyone know where to find it? I understand there are online resources, but I'd like to take a shot at adding this feature to my brew day spreadsheet.
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Old 02-01-2013, 08:09 PM   #2
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I use my phone, I dono if this helps?
https://play.google.com/store/apps/d...=com.BrewBuddy
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Old 02-02-2013, 12:16 AM   #3
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The best calculator for translating post ferment Brix readings to gravity readings that I have found is produced by Sean Terrill.
See http://seanterrill.com/2011/04/07/re...er-fg-results/ for details. He even provides spreadsheet templates for your convenience.
Personally, if there's any doubt, I take Brix readings to determine when fermentation is finished, and then take a single gravity reading with an hydrometer to determine what the final gravity is, and to judge the taste of the sample.

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Old 02-02-2013, 06:27 AM   #4
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Quote:
Originally Posted by ajf View Post
The best calculator for translating post ferment Brix readings to gravity readings that I have found is produced by Sean Terrill.
See http://seanterrill.com/2011/04/07/re...er-fg-results/ for details. He even provides spreadsheet templates for your convenience.
Personally, if there's any doubt, I take Brix readings to determine when fermentation is finished, and then take a single gravity reading with an hydrometer to determine what the final gravity is, and to judge the taste of the sample.

-a.
This. The Sean Terrill calculator is the best I've found and he shows all of his math/calculations.
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Old 02-02-2013, 07:15 AM   #5
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I recommend doing your own comparisons. When you collect enough data you will have a correction factor that you can plug into your software.
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Old 02-04-2013, 04:42 PM   #6
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Got the spreadsheet, will do my own comparisons. One of the reasons I do 4 weeks primary is to ensure the beer fully attenuates. Don't want to take the loss of a cylinder of wort daily. Hoping that with the smaller sample needed for a refractometer, I can take more frequent samples.

A point of edification; Why is Brix used in the calculators as opposed to SG? I have a dual scale refractometer, so I can use either. Just wondering.
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Old 02-04-2013, 06:01 PM   #7
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Most refractometers only have a Brix scale. If they have an SG scale as well, that is usually calibrated for simple sugar or fruit juice solutions, and is not going to be completely accurate for wort.

When I'm waiting for a brew to reach FG, I take a refractometer reading about once every 4 days, but don't bother to convert to SG. When I get two identical readings, 4 days apart, then I take an hydrometer sample to see what the FG really is. I tried using the refractometer and a calculator many years ago, but the results were not accurate.

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Old 02-04-2013, 06:59 PM   #8
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Quote:
Originally Posted by ajf View Post
The best calculator for translating post ferment Brix readings to gravity readings that I have found is produced by Sean Terrill.
See http://seanterrill.com/2011/04/07/re...er-fg-results/ for details. He even provides spreadsheet templates for your convenience.
Personally, if there's any doubt, I take Brix readings to determine when fermentation is finished, and then take a single gravity reading with an hydrometer to determine what the final gravity is, and to judge the taste of the sample.

-a.
Yes this is the one which has proven accurate for me. I actually tested it with hydrometer.
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Old 02-04-2013, 07:21 PM   #9
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It looks like Sean's is based on a large set of experiment data. Others I have seen seem to be based on the Balling observation or analytics.

Each tool has its place. Refrctometers are good at measuring refraction index. Hydrometers are good at measuring relative density. Neither are great at measuring final sugar or alcohol content because assumptions need to be made defining what "normal" fermentation is in order to use them. However, armed with both tools you can achieve more accurate measurements of alcohol and residual sugar.
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Old 02-06-2013, 05:54 AM   #10
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Quote:
Originally Posted by william_shakes_beer View Post
Got the spreadsheet, will do my own comparisons. One of the reasons I do 4 weeks primary is to ensure the beer fully attenuates. Don't want to take the loss of a cylinder of wort daily. Hoping that with the smaller sample needed for a refractometer, I can take more frequent samples.

A point of edification; Why is Brix used in the calculators as opposed to SG? I have a dual scale refractometer, so I can use either. Just wondering.
Brix/degrees Plato were originally used for wine making, they continue to use that scale rather than SG/density (vs refraction index). Wine is a simpler, more sugar/water only mixture than wort if I understand it correctly.
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