First All-Grain Batch Mash Paranoia

Discussion in 'Homebrewing' started by MmmmmmBeer123, Jan 3, 2016.

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  1. MmmmmmBeer123

    MmmmmmBeer123 Initiate (0) Nov 15, 2015 Connecticut

    1st post, 1st all-grain batch!

    Getting conflicting (I think) info on my first all-grain batch mash...any help is greatly appreciated!

    Grain bill:

    11# Rahr 2-row
    1# Flaked oats
    1# White wheat
    0.5# Caramalt
    0.25# Acid malt

    Brought 4 gallons of bottled spring water up to a temp of ~168F. Added the strike water to the mash tun cooler. Stirred in the grains. Temperature stabilized at around 153F. Tested the mash pH (was ~5.0).

    Tested a sample of the mash in a small white plate w/ tincture of iodine just to visualize (+) starch test...pretty obvious purple/black immediately upon putting a drop in.

    After ~1h in the cooler, temperature was ~148F. Iodine test looked negative for starch...no obvious change in the original iodine color.

    However, when I took a gravity reading, it only read as 1.042. According to the table on braukaiser for determining efficiency, I should have a first wort gravity of ~1.100 for 100% efficiency...but it seems that I only have 42% efficiency?

    Confused and don't want to do something stupid...will wait 15-30 minutes and maybe one (or more) of the BA homebrew gurus can offer some advice?

    Thanks in advance!!!
     
    #1 MmmmmmBeer123, Jan 3, 2016
  2. CarolusP

    CarolusP Zealot (590) Oct 22, 2015 Minnesota

    Is this a 5-gallon batch? If so, I don't think that's nearly enough grain to get a gravity of 1.100, so I'm guessing the math may be a bit off? A 1.042 gravity does seem a tad low, but not too far off from what I would expect.
     
    #2 CarolusP, Jan 3, 2016
  3. Mullen2525

    Mullen2525 Zealot (627) Dec 9, 2012 Massachusetts

    How large is the batch?

    When did you take the gravity reading and at what temp?
     
    #3 Mullen2525, Jan 3, 2016
  4. VikeMan

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

    What was the volume of the wort when you took the gravity reading? Also, what was the temperature when you took the reading, and did you correct for it?
     
    #4 VikeMan, Jan 3, 2016
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  5. VikeMan

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

    Not that a mash pH of 5.0 is likely to cause a huge efficiency problem, but why did you add the acid malt? Did you use mash pH software that predicted you'd need it?
     
    #5 VikeMan, Jan 3, 2016
  6. MmmmmmBeer123

    MmmmmmBeer123 Initiate (0) Nov 15, 2015 Connecticut

    @VikeMan - I was just following a recipe I saw for an IPA...not sure if I even needed it, TBH. I took the SG reading right from the mashtun...I added 4gal strike to the ~14# of grains for a 1.16qt/lb ratio. I would guess the temp was ~130-140F by the time I got it into the hydrometer column.
     
    #6 MmmmmmBeer123, Jan 3, 2016
  7. MmmmmmBeer123

    MmmmmmBeer123 Initiate (0) Nov 15, 2015 Connecticut

    @VikeMan - and actually, to be a bit more accurate, I used pH papers...the color was somewhere between the 5.0 and 5.4 shown on the vial, but looked closer to 5.0 (so maybe pH was like 5.1-5.2)
     
    #7 MmmmmmBeer123, Jan 3, 2016
  8. MmmmmmBeer123

    MmmmmmBeer123 Initiate (0) Nov 15, 2015 Connecticut

    @CarolusP and @Mullen2525 -

    5gal batch; targeting ~1.065ish OG pre-fermentation.

    Took the reading from a sample right out the mashtun (cooler); 4gal of strike water + the grains, est temp was something like 130-140F by the time I put it in the hydrometer column
     
    #8 MmmmmmBeer123, Jan 3, 2016
  9. VikeMan

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

    I would suggest never adding acid malt (or lactic acid or phosphoric acid) unless you know it's needed for your combination of source water and grain bill.

    You need to correct the reading because higher temps cause lower readings. Google up "hydrometer correction" or similar for a table or a calculator app.
     
    #9 VikeMan, Jan 3, 2016
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  10. VikeMan

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

    So, this was a pre-boil gravity measurement. What was your pre-boil wort volume? You can't compute efficiency without knowing that.
     
    #10 VikeMan, Jan 3, 2016
  11. MmmmmmBeer123

    MmmmmmBeer123 Initiate (0) Nov 15, 2015 Connecticut

    Everything is still in the mashtun cooler so I'm not sure of the exact volume at the moment? A best guess would be around 3.6gal if I assume ~10% water absorption by the grains, right?

    And I went back and did SG for temperature...corrected SG is 1.054-1.057 based on estimated temperature of sample...

    Advice on the acid malt is duly noted!
     
    #11 MmmmmmBeer123, Jan 3, 2016
  12. VikeMan

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

    For mash efficiency computed from a pre-boil gravity reading, you need to know how much wort makes it into the kettle. That's your pre-boil volume. Any other measured volume (or guess) won't be relevant.

    ETA: Why is it still in the mash tun?
     
    #12 VikeMan, Jan 3, 2016
  13. MmmmmmBeer123

    MmmmmmBeer123 Initiate (0) Nov 15, 2015 Connecticut

    Thanks for all your awesome (& timely!) advice, BTW!!!

    I hesitated to sparge because I assume there'd be no going back if there were major issues with the mash...so by now it's been mashing for about 1.5h or so...I think I'll just sparge and see what I get after all that is done (and I can get a pre-boil volume reading).

    If worst comes to worst, I have about 3# of light DME I could add (some of) into the kettle if the efficiency was lousy, I guess?
     
    #13 MmmmmmBeer123, Jan 3, 2016
  14. Mullen2525

    Mullen2525 Zealot (627) Dec 9, 2012 Massachusetts

    Grain absorption should be somewhere between .1 an .2 gallon per pound of grain is I remember correctly. Seem like you got the cart before the horse here though. With All-grain you should be calculating your water beforehand. You'll need to adjust for your system but if you use google you can find a calculator you like and work from there.
     
    #14 Mullen2525, Jan 3, 2016
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  15. Mullen2525

    Mullen2525 Zealot (627) Dec 9, 2012 Massachusetts

    You should sparge, yes. Do you have your sparge water heated? Run off your mash, add your sparge water, stir well, and just give the grain bed enough time to settle and run it off again.
     
    #15 Mullen2525, Jan 3, 2016
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  16. VikeMan

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

    Yes, sparge and then get a (new) pre-boil gravity reading and volume measurement. Correct the gravity reading for temperature. Then estimate your post-boil gravity to see if you need to add any of your DME.

    Example: Say your pre-boil volume is 6 gallons and your temperature corrected gravity reading is 1.040. And say you expect to boil-off one gallon to reach 5 gallons post boil. Estimate your expected post boil gravity thusly...

    40 x (6 / 5) = 48

    So expect 1.048 post-boil.

    Also, for reference, one pound of DME adds about 9 gravity points (.009) to 5 gallons of finished wort.
     
    #16 VikeMan, Jan 3, 2016
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  17. MmmmmmBeer123

    MmmmmmBeer123 Initiate (0) Nov 15, 2015 Connecticut

    Yes, I did do calculations for strike and sparge water amounts, but in my (mild) panic with odd results, did not review details on proper procedures to get to efficiency estimations...

    I also know now that I need to tweak my mashtun setup/filling procedure as I'm pretty sure I have quite a large amount of residual wort left in the cooler because my braided tubing attached to the drain "floated up" a bit with the strike water/grain additions (so it's not sitting nicely on the cooler bottom like it should be)...ended up only getting 5gal out from a total of 7gal of strike/sparge water...not too efficient there!
     
    #17 MmmmmmBeer123, Jan 4, 2016
  18. MmmmmmBeer123

    MmmmmmBeer123 Initiate (0) Nov 15, 2015 Connecticut


    OK...sparged and ended up getting a temp-corrected pre-boil SG of 1.050 and a volume of 5gal...

    If I expect about ~1gal boil-off during a 60min boil (from my extract brewing, that's typical for the pot that I'm using), then I get ~4gal post-boil and an est post-boil SG of 1.0625...not horrific...fairly close to my estimated OG of ~1.065

    I'll probably add a little DME (0.5# or so) just because...

    THANKS to everyone who offered advice!
     
    #18 MmmmmmBeer123, Jan 4, 2016
  19. Mullen2525

    Mullen2525 Zealot (627) Dec 9, 2012 Massachusetts

    That's about right. 13.75 pounds of grain absorbing 2 gal is .14 gal/lb grain absorbtion
     
    #19 Mullen2525, Jan 4, 2016
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