Different OG - Post boil gravity and Original gravity

Discussion in 'Beginners Brewing Forum' started by Mr. Paddedammen, Oct 22, 2019.

  1. Mr. Paddedammen

    Mr. Paddedammen New Member

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    Im new to this forum, so maby this have been discused a hundred times... Sorry for that.

    But why is it to two different OG in the set up? Why is post boil gravity and Original gravity different?

    upload_2019-10-22_18-39-57.png
     
  2. Nosybear

    Nosybear Well-Known Member

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    My guess would be that one number is a prediction (the Original Gravity) based on the recipe and the other (the Post Boil Gravity) is an actual measured quantity. It might be helpful, if this is the case, to label the values as "predicted" or "actual". I may have it backward because the "Post Boil Gravity" is labeled as an estimate. The green number is also an estimate.... I'm starting to see your confusion! The post-boil gravity makes no sense whatsoever! I was looking at one of my recipes and got this result:

    upload_2019-10-22_12-1-16.png

    The post-boil gravity is less than the pre-boil gravity! Unless I added water, that could not physically be. Until I know what that number actually means - help me out here, admins - I'll completely ignore it and focus on the green number, your predicted final gravity, and the pre-boil gravity which tells you you're starting out in the right place. Needless to say, I don't pay a lot of attention to this section of the brew session/recipe builder. The hop utilization, for instance, is confusing: It's way higher than I'd expect (normal utilizations are around 25% of dry hop weight), likely expressed as a percentage of available iso alpha acid.... It's kind of jacked up, when you get right down to it!
     
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  3. philjohnwilliams

    philjohnwilliams Well-Known Member

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    The stats list both a post boil size (volume) and a batch size, I would imagine that the difference in gravities has something to do with this. If you take the stats from the OP, we see a post boil size of 26L at 1.105 and a batch size of 21L. If you put these numbers into the dilution and boil off calculator, it gives you a gravity of 1.130 at the batch size of 21L.
     
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  4. Trialben

    Trialben Well-Known Member

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    Makes sense to me Phil.
     

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