LOW OG

Discussion in 'General Brewing Discussions' started by WCWMatt, Sep 20, 2018.

  1. WCWMatt

    WCWMatt New Member

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    Looking for suggestions to help solve my low OG issue. My last two brews I didn't hit my OG numbers, not even close. I've been all grain brewing with 4 batches under my belt. First two, great; last two, way off. Final results, interestingly, was still tasty beer, but I'd like to solve the problem. There are a couple of things I did wrong and am adjusting and they are: I was experimenting with my herms system and my mash temp was about 5 degrees higher than the recipe called for and second, I ordered the grains milled (didn't mill myself). I'm no milling expert, but I definitely get a finer product when I mill versus what I received when ordered. I can 'fix' both of these on the next batch, but any other suggestions for things I should be looking for?
     
  2. Hawkbox

    Hawkbox Well-Known Member

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    Was your pre-boil OG close or way out as well? I've realized lately I'm mashing to high and have ended up with high FG issues but it hasn't really affected the OG.

    Maybe the grain had been milled and sitting for a while before it shipped?
     
  3. WCWMatt

    WCWMatt New Member

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    Pre-boil was off as well. Not brewing this weekend, but next weekend for sure and I'll be milling here. At a minimum remove those two items as the issue - or hopefully it solves the problem
     
  4. Hawkbox

    Hawkbox Well-Known Member

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    Can you think of anything else you did differently in the batches that came out low? Taking lots of notes is a good idea too, then you can reference against them and see if you did something different without realizing it.
     
  5. J A

    J A Well-Known Member

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    Higher mash temp will likely result in reasonably consistent OG but lower FG...you'll be making sugars but they're less fermentable. Getting a good temp setting on the HERMS system requires accurate temp probe placement and careful PID programming. If you're not using a controller, it's tough to keep it consistent. I try to go by the warmest temperature of the mash as it comes out of the HERMS coil and ignore the grain bed temp. That's been treating me pretty well so far.
    If the low OG batches were both milled the same and not very fine, that's where I'd be looking for the solution. Crush is extremely important.
    Seems like you're still figuring out your system and procedure. I wouldn't be surprised at some erratic numbers at this stage of the game.
    You'll get it dialled in. ;)
     
  6. Trialben

    Trialben Well-Known Member

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    But OP is also getting Low OG so thats poor extraction in my bookso_O. Crush as JA indicated and Hawkbox will be part of the culprit. Yep mill it yourself but if you rely on a filtration mechanism other than BIAB material be careful of the stuck mash/sparge aswell...

    Hows your volumes too? Final volume on the money? If your overshooting obviously this will lower your gravity readings too.

    And last but not least poor conversion from too high mash temp could mean your actually killing of enzymes from too high a temp from hard working conditions too.

    What mash temp arebyou targeting? Go mid to low on the sacc range next brew incase as JA put it your temp readings are out coupled with your own mill i recon you just may have a win:).
     
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  7. White Haus Brews

    White Haus Brews Active Member

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    As long as you're not mashing over 170 I wouldn't blame a slightly higher mash temp for a low OG. The biggest culprit is likely the grain crush. The second thing I would look at is ending volume. If you use a 5 gallon recipe with a projected OG of 1.050 it would only be around 1.041 if you ended up with close to 6 gal without adjusting your grain bill. How off are you? And was it consistent between the 2 batches it happened with?
     
  8. vthokiedsp

    vthokiedsp Member

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    #8 vthokiedsp, Sep 20, 2018
    Last edited: Sep 21, 2018
    i'm not all that familiar with the HERMS system, but would your lauter pacing impact the OG? i vorlauf/lauter manually out of my mash tun and pace is my single greatest variable when achieving my target pre-boil OG. like so slow it's barely a trickle coming out of my tun. if slowing your lauter pace is an option in your system, try that. edit: slow applies to 1st and 2nd runnings.
     
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  9. J A

    J A Well-Known Member

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    Agree with that^^^...Pace of sparging will make a difference in rinsing the maximum converted sugars from the grain bed.
    I still think crush size may be a substantial part of the difference here.
     
  10. HighVoltageMan!

    HighVoltageMan! Well-Known Member

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    First thing is: What is your mash efficiency? If it's 75%, that's not real bad. The grain crush can have an impact, but that can be compensated by a constant vorlauf and extended mash times, too fine and you run into stuck mash/sparge. If you do crush super fine, rice hulls can help with circulation. Higher temps will not lower the the OG and will raise the OG in some cases. Your pH will also have an impact on your efficiency too, 5.4-5.6 at 80F is ideal.

    I would suggest step mashing as well, to take advantage of the HERMS system. I have a RIMS system and I get 85% or better efficiency almost every brew and never below 82%. I have a constant vorlauf (recirculation) during the entire mash, pH is spot on and I step mash. Typical schedule 145-149F for 60-90 minutes, 158F for 15 minutes and 168F for 10-15 minutes. The second and third steps will raise the mash gravity. I typically see it go from 1.068 to 1.078-80.

    You've got a great system, especially when you get it dialed in. It's way better and nicer than a cooler setup.
     
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  11. Hawkbox

    Hawkbox Well-Known Member

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    That's something too, when I do really high OG beers in my Mash Coleman I lose efficiency and drop OG because I can't do as good of a sparge. It might be a factor.

    I basically flour my grain when I mill it so I get away with some stuff that way too.
     
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  12. Trialben

    Trialben Well-Known Member

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    Same forme in BIAB big grain bills 6+kg my efficiency drops 10%
     
  13. WCWMatt

    WCWMatt New Member

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    What a great series of comments. A lot to work on and I'm looking forward to it. To answer a few questions, my volumes are hitting right on, I do a constant vorlauf (I haven't calibrated my temperature sensors since i first set up the system, I need to do that again). The efficiency on the last two batches was closer to 65%. I've never tried step mashing and although I don't think I'll try it with the next brew, I'm definitely going to work that in on a future run. My mash temp target was 154, but I was 160-162 for 60 minutes. I'm really liking the new setup and am anxious to get it dialed in so I can get some consistent repeat brews. I'll post again in a couple of weeks with the results......
     
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  14. J A

    J A Well-Known Member

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    I'd be expecting a pretty high FG out of that...even with a very attenuative yeast. Just not enough fermentable sugar and too much dextrine. Will probably still be a good, drinkable beer, though.
     
  15. Hawkbox

    Hawkbox Well-Known Member

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    Yeah, I just did a lager earlier today that is going to probably finish crazy low as I was aiming for 65C and ended up at 63C for my mash. Stupid garage I forgot to factor in ambient temperature. (Garage was 9C when I started). I don't have a good way to bring the mash temp up so I get what I get.
     
  16. Nosybear

    Nosybear Well-Known Member

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    I had an issue a while back and found an interesting solution to low mash temps, a sous vide cooker! Circulates and heats.
     
  17. Hawkbox

    Hawkbox Well-Known Member

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    Ooh that's an idea. And my wife would be on board with getting one I suspect.
     
  18. White Haus Brews

    White Haus Brews Active Member

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    It's a good excuse to also get a vacuum sealer too for resealing hops :p
     
  19. Nosybear

    Nosybear Well-Known Member

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    Got the zipper bags with the valve this afternoon!
     
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  20. WCWMatt

    WCWMatt New Member

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    We got a vacuum sealer last year and it has been awesome for storing hops and my wife loves it for whatever it is she does with it!!
     
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