Question from the typical noob

Discussion in 'Homebrewing' started by butterygold, May 12, 2020.

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  1. butterygold

    butterygold Devotee (343) May 12, 2020 Spain

    My first post here.

    I have a doubt. I just brewed my fourth beer - an Alpine Nelson clone - and I am worried about low ABV. I used about 14 pounds of grain and mashed for 90 minutes at 154º. The first problem is I might have had issues with my digital thermometer and maybe mashed lower than that. After the boil, I had about 3 gallons of wort, which I topped off with 2 gallons of water. After reading again and again 'use a hydrometer' I finally got one and - surprise - my brew measured a measly 1.020 when the target gravity was 1.064. It seems almost impossible to be that far off. Grain bill calculators said that at 70% efficiency I should have between 1,065 and 1.070. According to the calculations, this will give me an ABV of less than 3%. The only thing I can think of is that I took the sample from the top of the fermenter without mixing too much (I gave it 2 or 3 stirs, not wanting to introduce too much oxygen) and it was too watery.
    My real doubt is, after pitching 2 packs of Mangrove Jack's West Coast yeast, fermentation only lasted about 24 hours, judging by airlock activity (I know, I know) and presence of Krausen. Could this be because there was so little sugar for the yeast?
    This weekend I have to dump 45 bottles of a NE IPA that oxidized on me - yes, I have the dreaded purple cardboard. I really don't want to have to drain pour another batch.

    Thanks in advance.
     
    #1 butterygold, May 12, 2020
  2. Eggman20

    Eggman20 Crusader (433) Feb 14, 2017 Minnesota

    I would say its likely got be a mixing issue or a serious measurement error. To be at 1.020 with 14 pounds of grain (assuming mostly 2-row or pilsner) my calculations would have your efficiency around 20% and something would have to be very wrong to be that low. I wouldn't be too worried about adding oxygen when stirring in the water as your yeast will need some anyway at the start of fermentation. You just need to be cautious of adding oxygen post fermentation start.

    The rapid part of fermentations can happen pretty quick so I wouldn't worry too much about that. I'd let it ferment for a few days and take a hydrometer sample and see what the reading is. If it's higher than you started or close to it, you have your answer about the initial reading being in error. If the sample reads very low (under 1.010) and it tastes watery then it may be a lost cause.

    Side question: Does your current system keep you from being able to mash and/or boil the full volume? It'd help efficiency if you could use that in the mash or doing a sparge.
     
    #2 Eggman20, May 12, 2020
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  3. butterygold

    butterygold Devotee (343) May 12, 2020 Spain

    Thanks for the reply. The color looked good (except for the sample), so I still have hope.
    I used about 9 pounds pilsner, 2 pounds rye, 2 pounds Maris Otter and 1 pound carapils. I also think this is a pretty high amount to end up with that reading.
    As far as my setup goes, I only have a 5 gallon brew kettle. I need to get a bigger one so I can do all-boil.
     
    #3 butterygold, May 12, 2020
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  4. ECCS

    ECCS Pundit (755) Oct 28, 2015 Illinois

    Were u planning to do a partial mash and then top off with 2 gal water? Or was that an on-the-fly decision?
     
    #4 ECCS, May 12, 2020
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  5. butterygold

    butterygold Devotee (343) May 12, 2020 Spain

    It was the plan. But I didn't take a reading before adding the water. Doh!
     
    #5 butterygold, May 12, 2020
  6. PortLargo

    PortLargo Pooh-Bah (1,831) Oct 19, 2012 Florida
    Pooh-Bah

    Was your grain crushed?
     
    #6 PortLargo, May 12, 2020
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  7. butterygold

    butterygold Devotee (343) May 12, 2020 Spain

    Yes.

    I used the food processor for my ill-fated NEIPA, but I bought a mill for this brew. I used the second-finest setting.

    Thanks!
     
    #7 butterygold, May 13, 2020
  8. JackHorzempa

    JackHorzempa Grand Pooh-Bah (3,375) Dec 15, 2005 Pennsylvania
    Society Pooh-Bah

    It seems to me this is your 'disconnect' right here. You need to collect about 7-8 gallons of wort prior to the boil and after the boil end up with about 5.5 gallons or so of wort in order to achieve your target OG.

    If you want to continue brewing with your 5 gallon pot to brew higher gravity beers (e.g., OG = 1.064) you can use some malt extract to boost your gravity (i.e., a partial mash).

    Cheers!
     
    #8 JackHorzempa, May 13, 2020
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  9. butterygold

    butterygold Devotee (343) May 12, 2020 Spain

    Thanks for the reply. A bigger kettle is definitely the next purchase.
     
    #9 butterygold, May 13, 2020
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  10. butterygold

    butterygold Devotee (343) May 12, 2020 Spain

    Hello again,

    A quick update: today was bottling day and the final gravity reading was about 1.010. The recipe target was 1.018. Is that real far off?
    It looks good, smells good and doesn't taste watery. I now assume that my initial reading of 1.020 was not correct.
    How can I calculate ABV now?

    Thanks
     
    #10 butterygold, May 23, 2020
  11. riptorn

    riptorn Pooh-Bah (1,776) Apr 26, 2018 Georgia
    BA4LYFE Society Pooh-Bah Trader

    The formula is (OG - FG) x 131 = ABV %
    A web search for ABV calculators will return many plug and play online calculators.

    If your assumed OG of 1.020 was correct and if the FG of 1.010 is also correct, the ABV comes in at about 1.3%.
     
    #11 riptorn, May 23, 2020
  12. butterygold

    butterygold Devotee (343) May 12, 2020 Spain

    Thanks for the formula. I found a calculator, but as I don't really know the OG, I can only play with assumptions. If I put in an OG that is about as off the recipe targets as the FG was, it gives me an ABV of about 6.8%.

    The hydrometer sample I later drank certainly didn't taste like it was 1.3%!
     
    #12 butterygold, May 23, 2020
  13. riptorn

    riptorn Pooh-Bah (1,776) Apr 26, 2018 Georgia
    BA4LYFE Society Pooh-Bah Trader

    I misread that part.....overlooked "not" before correct.
     
    #13 riptorn, May 23, 2020
  14. ssam

    ssam Pundit (997) Dec 2, 2008 California

    The only way to measure ABV with incorrect initial measurements would be to physically measure the volume of alcohol by distilling. Not something a typical homebrewer can do. You can guess what your efficiency was and get an estimate for OG that way then do the calculation, but it will only be an estimate.

    Mix well when you top off with water. You want oxygen at that stage and you also want homogenization for accurate readings.
     
    #14 ssam, May 26, 2020
  15. butterygold

    butterygold Devotee (343) May 12, 2020 Spain

    That's the answer I was looking for. Thanks! Live and learn.
     
    #15 butterygold, May 27, 2020
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