Predicted OG in Brew Session doesn't match measured value

Discussion in 'Brew Sessions' started by formula155, Mar 24, 2020.

  1. formula155

    formula155 New Member

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    Hi,

    I created a recipe, and started a brew session, but in the session the predicted OG seems very high, and did not match my measured value (predicted 1.048. measured 1.039). The beer is an ESB.

    Now that fermentation is under way, I currently have a gravity of 1.014, below the predicted FG of 1.017.

    I am using a Tilt for SG readings. The brew session is here.

    https://www.brewersfriend.com/homebrew/brewsession/327927

    Anyone have any idea why the discrepancies?

    Thanks,

    Guy Montgomery
     
  2. Yooper

    Yooper Administrator
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    First, did you calibrate your Tilt? That could be one thing. Secondly, did you adjust your efficiency to the proper efficiency? If you missed your OG, and you took an accurate hydrometer measurement, that's the first thing to do. Adjust your efficiency in the Recipe Builder to your actual efficiency, so that you start with an accurate measurement.
     
  3. formula155

    formula155 New Member

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    I have not calibrated this particular tilt, but I have another and it was very accurate as delivered. I will do a cal, but don’t really suspect that as an issue.

    One thing that was an issue, and I have seen this before with a Tilt, is that some yeast was stuck on the tilt, which was definitely affecting the reading. When I transferred to my secondary I cleaned off the yeast and the SG jumped from1.009 to 1.014, so this has definitely helped with the attenuation.

    In terms of efficiency, should I be taking the actual efficiency of, say, the last few sessions and taking an average to establish my actual efficiency? And why would my efficiency not match the recipe?

    Thanks for the feedback.
     
  4. Pricelessbrewing

    Pricelessbrewing QA Software Tester
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    Efficiency will vary depending on a number of factors, but assuming you use the same process and equipment for every recipe you brew (never varying batch size, whether you sparge or not, how long you boil etc).

    The efficiency should be consistent with a similar amount of grain (or OG) used. A 1.055 recipe will usually be around 70-75%, while a 1.040 recipe is usually around 75-80%, and a 1.085 recipe may be as low as 60-65%. There's a lot of good information out on the web regarding this, but each brewers average, and the curve for that trend, will be slightly different.

    When setting an efficiency, look at where your average is overall, and any other similar recipes you've made and make your best guess based on that information.
     

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