First AG - Low efficiency

Discussion in 'Homebrewing' started by TastyAdventure, Dec 10, 2013.

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  1. TastyAdventure

    TastyAdventure Initiate (0) Nov 13, 2012 Kentucky

    I just did my first all grain batch. I've done a few Partial Mashes before, with efficiencies of 60% 75% and 80%. For this first AG batch my efficiency was 60%. I made a bazooka tube with a stainless steel braid from a toilet water supply line for the bottom of my 10 gal Gatorade cooler. The run off was very fast. I hit all my temps and mashed 10 lbs of grain with 15 qts for 50 min. Then I batch sparged with 17 qts. Ended up with probably 6.75 gal of pre boil wort. Boiled for about an hour 20 min, and had to top off with a half gallon in each kettle. (I did two separate boils for 2 separate 2.5 gal batches). Like I said, I got about 60% efficiency and can't figure out why.
    Any help would be great. Thanks!
     
  2. koopa

    koopa Initiate (0) Apr 20, 2008 New Jersey

    60% mash efficiency or brew house efficiency?

    If mash efficiency, then the first thing to examine would probably be the quality of your crush.
     
  3. PortLargo

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

    Your low efficiency was due to the top off addition. A half-gallon addition to 3.75 volume is 15% (dilution factor). Your 60% efficiency adjusted for 15% dilution equals 70.5%, about what you expect for batch sparging. Your options to keep efficiency up is to delete the top off . . . accept a lower volume. If you want more volume then add grain and sparge more.
     
  4. VikeMan

    VikeMan Grand Pooh-Bah (3,067) Jul 12, 2009 Pennsylvania
    Pooh-Bah

    Not sure I'm following you, but mash efficiency does not change with volume (due to boiling off or topping off). Gravity does, but efficiency does not. IOW, in OP's case, boiling off more water than expected, and then topping off with more water doesn't change efficiency.

    Now, it's possible that OP measured gravity at a volume other than expected, and didn't adjust the efficiency calc for the difference in volume.

    OP: What was your grain bill, OG, and the volume of wort when you measured the OG?
     
  5. JohnSnowNW

    JohnSnowNW Initiate (0) Feb 6, 2013 Minnesota

  6. TastyAdventure

    TastyAdventure Initiate (0) Nov 13, 2012 Kentucky

    Well the reason I said my mash efficiency was low is bc my brewing app said my OG should be 1.057 post boil at 2.5 gallons, and it was actually 1.048 post boil and post top off at 2.5 gal. I was scrambling for a boil off calculator but couldn't figure it out, didn't want to risk ending up with too much and figured topping off would be better. It looks like my boil off rate was higher than standard, probably bc of the split boils...
    My grain bill was 10 lbs.
     
  7. koopa

    koopa Initiate (0) Apr 20, 2008 New Jersey

    If you had 6.75g preboil and ended up with 5 gallons post boil after adding 0.5 gallon x 2, then you boiled off 2.75g between the 2 boils in 80 minutes. That works out to 1.375 gallons per 80 minutes per boil, or 1.03 gallons per hour per boil which is fairly standard.

    While the percentage can be reverse engineered from your post boil volume and post boil gravity (by factoring in your boil off rate), mash efficiency is generally based off of your preboil volume and preboil gravity.

    Try to get into the habit of measuring your preboil gravity as it will make it easier for you to calculate your true mash extraction in the future.
     
    #7 koopa, Dec 10, 2013
    Last edited: Dec 10, 2013
  8. VikeMan

    VikeMan Grand Pooh-Bah (3,067) Jul 12, 2009 Pennsylvania
    Pooh-Bah

    If I read all of your info right, you used 10lbs of grain, and ended up with 5 gallons of wort @ 1.048. Now, the type of grain matters, but assuming an average of about 36 PPG fo your grains, your mash efficiency was about 67%.
     
  9. VikeMan

    VikeMan Grand Pooh-Bah (3,067) Jul 12, 2009 Pennsylvania
    Pooh-Bah

    You can also use post-boil volume and gravity, as long as you're willing ignore the small volume typically added by the hops, or adjust the final volume downward to account for them. But with most recipes, the difference is negligible.
     
  10. PortLargo

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

    Thanks for the correction . . . also good read from JohnSnow's link . . .
     
  11. koopa

    koopa Initiate (0) Apr 20, 2008 New Jersey

    Very true and thanks for the correction. You actually caught me with my pants around my ankles before I had time to pick them up by editing my post / adding elaboration. I was trying to focus on the easiest way to measure it moving forward for the OP, which I believe is to generate mash extraction based off of a preboil volume measurement and preboil gravity reading. But I guess you could go by your post boil gravity and post boil volume just as easily, provided you know not to get confused and go with your volume in the fermenter since factoring those the transfer losses in would skew your extraction efficiency into a brew house efficiency measurement.
     
    #11 koopa, Dec 10, 2013
    Last edited: Dec 10, 2013
  12. TastyAdventure

    TastyAdventure Initiate (0) Nov 13, 2012 Kentucky

    Ok now I'm confused about gravity readings. My brew app tells my what my OG should be, and that's post boil right? What's the equivalent preboil gravity? It wouldn't be the same, right?
     
  13. koopa

    koopa Initiate (0) Apr 20, 2008 New Jersey

    Generally your OG = post boil. Your preboil gravity will always be lower than your post boil gravity, since you are evaporating water during the boiling process which increases the sugar concentration of your wort. What brew app are you using? I use beersmith and it makes preboil gravity predictions, post boil gravity predictions, and post fermentation final gravity predictions.
     
  14. JohnSnowNW

    JohnSnowNW Initiate (0) Feb 6, 2013 Minnesota

    What app are you using?

    OG usually means gravity post-boil.

    Preboil and OG are not the same.
     
  15. VikeMan

    VikeMan Grand Pooh-Bah (3,067) Jul 12, 2009 Pennsylvania
    Pooh-Bah

    It would not be the same. It's related by this formula...

    (PreBoilOG - 1) * (PreBoilVolume) = (PostBoilOG - 1) * (PostBoilVolume)
     
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