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Taking OG from protein and sediment-heavy wort

Discussion in 'Homebrewing' started by atomeyes, Dec 8, 2012.

  1. i hate wasting good wort. so if i'm taking my gravity readings after racking my just-chilled wort from the kettle, i like to use the crap that's full of proteins and hop grit n stuff.

    i assume that the fact that it isn't pure wort (i.e. the wort that's going into my carboy) will affect my OG. i assume that it will increase it by a few points due to higher density.

    but...that wort is a slurry....but using the definition of density, you have mass over volume. so that gunk should affect gravity. but by how much?

    i just did a belgian strong ale. target OG was 1.092. my OG was 1.100. now, that's not much of a variance, but I'm curious if the variance was due to my temperatures or water measurement, or if it was from the sludgy wort that was measured. and is my true gravity BELOW 1.02?

    so many questions this weekend...
  2. Sludgy wort shouldn't make a difference. You're hydrometer is measuring the sugar dissolved in solution. All of the "sludge should settle to the bottom and not make a difference on your actual gravity measurement. Just make sure the bottom of the hydrometer isn't resting on the sludge.
    bgjohnston likes this.
  3. cool.
  4. inchrisin

    inchrisin Savant (425) Indiana Sep 25, 2008

    I'm surprised that someone hasn't taken a reading from a refrac and verified it against a hydrometer. It has to be the same or very close.
  5. bgjohnston

    bgjohnston Savant (350) Connecticut Jan 14, 2009

    We did just that at a brew day sponsored by my local shop, and my hydrometer measured within 2 points of another guy's refractometer. And it was very sludgy wort with a lot of hop debris in my sample.
  6. Shit suspended in the wort will influence the reading but not by much. Wort/beer should be filtered if you want a truly accurate reading.
  7. inchrisin

    inchrisin Savant (425) Indiana Sep 25, 2008

    I would take a pre-boil gravity if I DON'T FWH. I know how much I boil off in an hour and how many GU I have. I can find an OG pretty easy.

    Edit: That said, I usually don't measure anything anyway. :)
  8. i've been leaning towards not measuring. kind of argue with myself as to why i'm measuring. except today, i'm staring at a belgian strong that's 3 days in with zero fermentation happening. so i am sure i'll be measuring something pretty soon.
  9. That's really the way to go once you learn your system. I'm not going to worry about a point or two and will never know the difference if I don't take a measurement. One less thing to fret about.

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