Conversion?

Discussion in 'General Brewing Discussions' started by MrBIP, Nov 17, 2013.

  1. MrBIP

    MrBIP Active Member

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    Upon completing my first all grain day, I sat down and entered all my numbers in the brew log.
    I had a 1.040/1.042 (hydrometer no always easy to read, so I entered 1.041) after collecting 7.5 gallons in my brew pot. So I entered that. I used 9.5 total gallons (5.5 gallon strike, 4 gallons batch sparge).
    It's giving me a conversion percentage of 103.2%. Which can't be right (it can't be more than 100%, right?)
    So, I'm wondering if there's something I'm missing, not understanding or measured incorrectly.

    Info:
    I had 11 pounds of grain, 5.5 gallon strike 60 minute mash, 4 gallon batch sparge 30 minutes; collected 7.5 gallons.
    First runnings OG 1.08 4 gallons, second runnings 1.027 3.5 gallons, "blended"/in the kettle/pre-boil 1.041, finished 5.5 gallons at 1.06 (target was 1.058). Brewhouse efficiency/Ending Kettle efficiency calculated 71%, pre-boil 76%.

    MrBIP
     
  2. Ozarks Mountain Brew

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    your hydrometer should be read at 60 or what ever the instructions read for that hydrometer then you can offset to a different temp sometimes so the reading could be off
     
  3. Nosybear

    Nosybear Well-Known Member

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    I'm not an expert on the software but somehow, I'd bet, it's thinking you got 9.5 gallons of wort at 1.041 for 389.5 total gravity points, or three percent more than should be in the fermentables. If you convert that to 7.5 gallons of wort at 1.041, you get 307.5 gravity points for a conversion of about 81%, which based on your brew house efficiency, sounds about right.

    I've gotten those strange conversion numbers, too. Not sure exactly how but for me it usually occurs when I don't mash everything (late additions of sugars, for example).
     
  4. MrBIP

    MrBIP Active Member

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    I probably should set about calibrating my hydrometer. Never have before as I was always hitting the numbers, perhaps it's more important now.

    I did have a late addition of sugar in this, but that 1.041 was pre-boil, so figured it was the right number, now I'm wondering if I've misread something in there and maybe I'm not putting the right numbers in the right places. Wonder if that late sugar is faking out my efficiency too.

    Planning to brew again next weekend, so will have something to compare to at that point.
     
  5. Nosybear

    Nosybear Well-Known Member

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    There's where the conversion issue came in - the late sugar addition. Sugar is utilized at 100% and yields about 47 point pounds per gallon (if you dissolve a pound of sugar in a gallon of water, you'll get a 1.047 wort). Grain's maximum yield is about 36 ppg but if you mash a pound of grain, you don't get 36 ppg, more like 25 at a 70% yield. I just punched a 1 gallon batch using 1 pound of sugar and 1 pound of American pale 2-row. I get a 1.072 wort, or 72 ppg. 47 of them are from the sugar, leaving 25 points for the grain - cross check is good. But I've noticed that late sugar additions whack out the efficiency calculations (sorry, Larry!) so in general, I do one of two things: I ignore the conversion results which ultimately have no bearing whatsoever on me as a homebrewer as long as I'm close to my target gravity or, if I'm feeling particularly geeky, I'll enter the grains only into the calculator and calculate the effect of the late additions by hand. Which is likely the best route, as the gravity of the wort during the boil affects bitterness.
     
  6. Ozarks Mountain Brew

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    I'm with you all I'm worried about is final gravity which is 2 things, final mouth feel and is the beer really done fermenting. everything else is just something to document and face it grain, temperature, humidity, boil time viscosity, all that always changes from brew to brew so no 2 beers are really the same just close lol
     
  7. Nosybear

    Nosybear Well-Known Member

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    How far off is your hydrometer? Get some distilled water to 60°F and take a gravity reading. Be sure of how to read your hydrometer - some read at the top of the meniscus and some at the bottom but it really doesn't matter as long as you read the same way every time. Read your gravity and see how far off 1.000 you are. If you're above, say 1.002, you'll have to subtract 2 points from every gravity reading and vice versa. My observation is it's pretty impossible to read them accurately to one point or two - the usual graduation - due to foam, opaque wort, inability to find the bottom of the meniscus, etc. I use a refractometer when brewing and it's usually about two or three points off my hydrometer so my approach? RDWHAHB. A point or three doesn't make that much of a difference.
     
  8. Nosybear

    Nosybear Well-Known Member

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    As to "beer done fermenting," the same reading three days in a row, regardless of how you read the hydrometer or how far it's off, is a good indication of done. Your yeast will continue clean-up for some time, that's why I generally don't recommend cold crashes.
     
  9. MrBIP

    MrBIP Active Member

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    Understood, but ... the 1.041 I entered in the brew log was the gravity of both first and second runnings, pre-boil, 7.5 gallons in the brew kettle, net of the 9.5 gallons of water I used in mashing. The sugar wasn't added until flame out. It doesn't seem that it should affect the calculator unless it's going back to the recipe and using it? Now I'm going to have to go an look up the actual calculation for myself and learn something, instead of just letting the computer do it for me, darn. :geek:
     
  10. Tom McLean

    Tom McLean New Member

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    I have had the same experience. As it worked out, I took a SG sample while sparging, which was higher then the average.

    I now take a sample after the kettle is filled, but before boiling and also I get a volume measurement then. I also get a SG sample and volume measurement after the fermentor is filled. I calculate the gravity points from both and then see what is going on with the brewery. All of the readings need to be temp. corrected and the two sets of gravity points should be about the same if everything was done correctly. If they aren't close to the same you need to see where your measurments went wrong.

    Tom McLean
    On the Wet Coast,
    After the Storm
     
  11. MrBIP

    MrBIP Active Member

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    This outcome makes a much more sense than last week; 76.8% conversion, 67% brew house efficiency.
    I must have have read something wrong/measured incorrectly last week.
    The hydrometer I have is calibrated to 60; verified with a water sample, so today I paid attention to temps of my samples.
     

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