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Possible reasons for a negative ABV?

Discussion in 'General Homebrew Discussion' started by CyrusBrewing, Dec 3, 2017.

 

  1. #1
    CyrusBrewing

    New Member

    Posted Dec 3, 2017
    I 'completed' my first beer fermentation a few days ago. From the initial and final specific gravity, I ended up with a ABV of -120%. I'm really interested in finding the reasoning for this since it doesn't make any theoretical sense. Has anyone had this issue before.

    I didn't do the calculations wrong but it is possible I recorded the specific gravity incorrectly. Although I did double check at the time, so I don't think so.

    I did accidentally add the yeast at 26oC as I wasn't aware which temperature it should've been added initially. Could this have resulted in a negative ABV?
     
  2. #2
    FunkedOut

    FunkedOver

    Posted Dec 3, 2017
    What were the readings you took?
     
    jalc6927 likes this.
  3. #3
    MaryB

    Well-Known Member

    Posted Dec 3, 2017
  4. #4
    fofusak

    Well-Known Member

    Posted Dec 3, 2017
    I agree that we need the readings.
    MaryB' s theory sounds good, the numbers would either confirm it or give other clues?
     
  5. #5
    CyrusBrewing

    New Member

    Posted Dec 3, 2017
    The readings were OG = 1.038 and FG = 2.3 (It ended up being -165%, not -120 as my post says). Switching the OG and FG wouldn't change anything as a +165% ABV wouldn't make sense either. Nor would reading the right number wrongly (The number is very off, not close to where it should be). The only thing that makes sense to me at this point would be the completely wrong number was recorded.
     
  6. #6
    Pkrd

    Supporting Member  

    Posted Dec 3, 2017
    FG was likely 1.023.
    Thats quite a high value(ideally it would be around 1.008) and indicates fermentation was not complete.
     
  7. #7
    RM-MN

    Supporting Member  

    Posted Dec 3, 2017
    Your FG reading is an error. When you get a reading like that you will soon realize that the yeast cannot increase the sugar content so that high reading is impossible. From there on your calculations were wrong. Garbage in, garbage out. Take another reading and see if you don't get something much lower. Once possible cause for such a high reading is your hydrometer wasn't really floating in the wort but was resting on the bottom of the sample tube.
     
  8. #8
    flars

    Well-Known Member

    Posted Dec 3, 2017
    Is it possible the 2.3 reading was read off the balling scale instead of the specific gravity scale. The 2.3 on the balling scale would line up with approximately 1.010 on the specific gravity scale. This would be a normal final gravity for an American ale yeast.
     
  9. #9
    LLBeanJ

    Supporting Member  

    Posted Dec 3, 2017
    Negative ABV isn't a thing. It's not even possible. You either have alcohol present or you don't. I think flars' explanation is most likely what happened, but it was most definitely a measurement error of some sort.
     
  10. #10
    Ogroat

    Well-Known Member

    Posted Dec 3, 2017
    This seems like a perfectly reasonable explanation for a multi-scale hydrometer.
     
  11. #11
    ancientmariner52

    Supporting Member  

    Posted Dec 4, 2017
    If you drink to much negative alcohol, you may become knurd. You have been warned!
     
    Brewenstein likes this.
  12. #12
    Pkrd

    Supporting Member  

    Posted Dec 4, 2017
    This is great. Just chug three of them before driving home from the Pub. No wurries orificer.
     
  13. #13
    MaxStout

    Well-Known Member  

    Posted Dec 4, 2017
    And you get your wife back, your dog back, your job back...
     
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