Low Final Gravity

Discussion in 'Beginners Brewing Forum' started by MalW, Feb 2, 2021.

  1. MalW

    MalW New Member

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    Hi Guys,
    I have a stout in the fermenter now, that looks like it has finished way lower than expected.
    Measured with the hydrometer it started out at 1.088 and looks like it has finished at 1.005, just under 11% ABV
    The estimated FG should have been about 1.020.
    My question is, would that FG be right or does the alcohol affect the reading?
    Other info, the Mash temp was 67 C for an hour, boil was 2 hours, it did end up with 1.75 Kg (3.8 lb of Honey) in with the boil as I didnt have any DME that the recipe wanted.
    Any assistance would be much appreciated.

    Cheers
    Mal
     
  2. Bubba Wade

    Bubba Wade Well-Known Member

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    If you are using a float hydrometer, your reading should be accurate, as long as the sample temperature is close to the calibrated temperature. If you are using a refractometer, the alcohol will skew the reading.
     
  3. Megary

    Megary Well-Known Member

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    What yeast did you use? 94% attenuation is pretty unlikely for most yeasts, especially in a stout/porter (those dark worts always seem to be a bit less fermentable to me). Of course, your honey addition surely helped with that.

    Did you taste it? Did you notice any off flavors?
     
  4. AHarper

    AHarper Well-Known Member

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    I consistently achieve lower FG than that defined in the Recipe Builder stats. I think my fermentation fridge gives the constant temperature and other conditions to ensure good yeast activity. The attenuation levels are always greater than the published % for the yeast.
     
  5. HighVoltageMan!

    HighVoltageMan! Well-Known Member

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    That will cause a very low FG. That's a lot of sugar, you wouldn't use honey unless you wanted to dry the beer out (taste less sweet). Is this a 5 gallon (21 liter) batch?
     
  6. MalW

    MalW New Member

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    temperature pretty close to 20 c
     
  7. MalW

    MalW New Member

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    The yeast was Lallemund's Nottingham, the batch was 45 L (~ 11Gal) and I hit that with 4 x 11g rehydrated packets with some nutrient
    As for the taste, it tastes OK, i cant say there are any off flavors or smells except for the alcohol very noticeable
     

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  8. MalW

    MalW New Member

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    Hi HVM,
    It was a 45 Liter brew, i didnt know about the Honey drying out the beer but it will come in handy as i have made a few batches that have come out a bit sweeter than i would like
     
  9. MalW

    MalW New Member

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    Hello AHarper
    I have a double door commercial display fridge that i picked up second hand and i run that with a temperature controller, so the temperature is pretty constant, I did this ferment at 18C I forgot to mention in my other replies that I did give it a good 20 second burst of pure Oxygen a couple of hours after i pitched the yeast,
    I am using a stainless conical and this is only my second batch using it
     
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  10. Nosybear

    Nosybear Well-Known Member

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    Alcohol skews the refractometer reading higher than the actual gravity. Hydrometers are easier for beginners to use.
     
  11. MalW

    MalW New Member

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    Hello AHarper
    I have a double door commercial display fridge that i picked up second hand and i run that with a temperature controller, so the temperature is pretty constant, I did this ferment at 18C I forgot to mention in my other replies that I did give it a good 20 second burst of pure Oxygen a couple of hours after i pitched the yeast,
    I am using a stainless conical and this is only my second batch using it
    Hi Bubba,
    Nope I didnt use a refractomer
     

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  12. MalW

    MalW New Member

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    here is the actual reading
     

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  13. HighVoltageMan!

    HighVoltageMan! Well-Known Member

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    The use of sugar (honey) will greatly drop the FG. It really doesn't belong in a stout. It will works in Belgian Tripels, Quads and American double IPA's to keep them from becoming cloyingly sweet and still maintain a very high alcohol content.

    You used @ 4 pounds of honey in a 11 gallon beer. Honey has @ 35 ppg, so by using that much honey you brought the OG up by 1.013. When this ferments, nearly all the gravity goes toward alcohol and CO2 and will cause the gravity to drop more than .013.

    In other words, if you skipped the honey, the OG would have been 1.075 and it would have finished higher than 1.005. It's possible to be over 1.010 for a final gravity without the honey because it nearly all goes to alcohol which has a specific gravity lower than water (1.000). That's why sugar in Belgian beers work so well in getting very low FG's and keeping them very drinkable.
     
  14. MalW

    MalW New Member

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    Thanks HVM,
    Ive got it now, should not have used the Honey,
    Just need to decide if i keep it or just tip it and go start again, I dont really have enough room for bad beer
     
  15. HighVoltageMan!

    HighVoltageMan! Well-Known Member

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    Noooo..... don’t dump it! Taste it first, it may be good.
     
  16. Craigerrr

    Craigerrr Well-Known Member

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    One must at least taste that which one has brewed. Drinking ones mistakes, makes one a better brewer...
     
  17. SabreSteve

    SabreSteve Well-Known Member

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    Some mistakes are still pretty tasty too
     
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  18. AHarper

    AHarper Well-Known Member

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    most of mine weren't....
     
  19. SabreSteve

    SabreSteve Well-Known Member

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    Maybe I'm lucky?
    Or maybe I have lower standards?:D
     
  20. MalW

    MalW New Member

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    Ha Ha Thanks guys,
    I had a look yesterday and could not find any beer styles that have an FG as low 1.005, if it turns out to be tasty I will have to call it table wine
     
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