Low Pre-boil Gravity (pH issue?)

Discussion in 'Homebrewing' started by BeerMaverick, Jan 5, 2016.

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  1. BeerMaverick

    BeerMaverick Zealot (718) Dec 14, 2010 Connecticut

    Hi all, I've made a few all-grain batches and I've never had any real issues hitting my numbers (I use BeerSmith). I'm very familiar with the software and hit all my normal variables that usually affect preboil gravity (temp, vol, crush, time, etc.). Thus I was shocked this weekend when I was shooting for 1.065 and got 1.038....here is my grain bill:

    12# Pale 2-Row (@ mash)
    3# rolled oats (@ mash)
    1# victory (@ mash)
    2# roasted barley (@ vorlauf - fly sparge)
    1# chocolate (@ vorlauf - fly sparge)

    The rolled oats are at about 15% of my grain bill, so I mashed for almost 2 hours to ensure conversion (they have 0 DP, so they utilized the 2-row for conversion). I mashed at 153 F. There are only a couple reasons I came up with:

    1. Mash pH too high: I've never done any water calcs/additions since I've never had a problem with water before (though I've never brewed at this location, so that changes things). The water I used has a pH of 7.5 per water report (city water, not well water, so report should be accurate). I know ideally mash pH should be 5.1 - 5.6, so I'm worried that the pale grains I mashed with might not be enough to bring it down this low (does anyone know for sure based on the grain bill above?). I know the dark grains may have helped me if this is the issue because they're more acidic, but I was following Gordon Strong's advice of adding at vorlauf (never had issues with this before).

    2. I added the oats to the top of the mash (after the pale and victory), but stirred well I believe- perhaps I didn't stir enough ensuring that they're in contact with the 2-row for good conversion?

    Anyhow, I was wayyyyy off my target. Based on the above information (tried to get it all here since I know most answers are just more questions usually haha), does anyone have any ideas that I don't or should I start thinking about water adjustments....would a slightly high pH really throw it off that much? Thank you.
     
  2. DunkelFester

    DunkelFester Zealot (607) Aug 24, 2004 Pennsylvania

    I doubt pH is to blame. Intuitively, I'd say if you were really off by ~ 40%, it's something else. Like:

    1. You forgot to adjust for temperature when you took your hydrometer reading. 1.038 at 165F is 1.062 after temperature correction.
    2. A weighing error or broken scale.
    3. A crush problem. (Gaps on rollers need to be checked regularly - if the gap's too wide, you'll certainly have lower extraction efficiency)
    4. over-sparging (was there more wort left in your mash tun than you expected after you'd collected your runoff?)

    just a few ideas that seem more likely to me than a pH issue.
     
  3. wspscott

    wspscott Pooh-Bah (1,958) May 25, 2006 Kentucky
    Pooh-Bah

    Any chance your thermometer is off?

    As you say, it is the mash ph that matters, not the water ph. If you post the water report, someone could help you with the calculations to see if your mash ph was potentially off. FWIW, the city report is not necessarily accurate. There is a huge amount of variation in my water based on different Ward Labs reports that I have seen.
     
  4. utahbeerdude

    utahbeerdude Maven (1,374) May 2, 2006 Utah

    It's unlikely (if not impossible) that your mash pH was so far off as to affect mash efficiency that much (see this article). The pH of your strike water is essentially irrelevant; much more important to determining the mash pH is the alkalinity of your strike water.

    I'll second @DunkelFester's suggestions as to why things went wrong.
     
  5. BeerMaverick

    BeerMaverick Zealot (718) Dec 14, 2010 Connecticut

    Thank you all for your input. @DunkelFester I don't believe any of those are an issue for me. I adjusted the temps for my ATC refractometer into its range (I also checked a few readings with my hydrometer side-by-side to make sure it didn't need calibrating). Both the grain mill and scale I used were those of my local homebrew shop and they're very good, so I doubt those pieces of equipment were off (though it's possible). I've used them plenty of times before though and never had a problem. Regarding over-sparging - I used the water volumes in beersmith for the grain bill I had (7 gallons in mash tun and sparging with 4.5 gallons in HLT for a pre-boil volume of 8.25 gallons). In terms of the water I used, as I mentioned a pH of 7.5 and I know it's very soft water 14 mg/L (where I've seen that 0-60 mg/L is very soft). The only thing any of you mentioned that I'm not sure about is the thermometer - I'll check it to see if it needs calibrating (I doubt its very far off though).
     
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