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Maris Otter SMaSH - low FG

Discussion in 'All Grain Brewing' started by krz, 15/5/19.

 

  1. krz

    Well-Known Member

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    Posted 15/5/19
    Currently fermenting a Marris Otter SMaSH using Citra hops.
    It was mashed at 64.4C (normally I mash warmer) , it was 1.050 when I pitched it 5 days ago on 10/5/19.
    Ive been keeping it at 21C, but yesterday it was 1.008 so I raised temp to 23C.
    Its now 1.007 and still bubbling away, and Ive never before had a gravity reading this low before, normally my FG is 1.010 or 1.012.

    1. Should I be worried?
    2. I'm thinking the low mash temp is causing the FG to get lower. What do you think?

    I also bought a tilt2 hydrometer, and this is the first time Ive used it.
    For those that want to have a look, check this link https://docs.google.com/spreadsheet...v54R2xj9v3VcLE/edit?ts=5cd69b77#gid=734290882
    Click on Chart to see a pretty graph.
    Note: I started logging the day after I pitched.
     
  2. MHB

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    Posted 15/5/19
    Two obvious possibilities -
    Yes mashing cooler will make the wort more fermentable, you haven't said what yeast you are using but >85% AA is very high.
    You aren't reporting accurately, either your mash temperature or your new hydrometer aren't telling the truth (or even both).
    I would calibrate your hydrometer in very pure water (Distilled, Reverse Osmosis...), be a good idea to see how accurate your thermometer is while you are at it.
    Mark
     
  3. krz

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    Posted 15/5/19
    Thanks.
    Yeast us-05. Also, I did calibrate the hydrometer in melb tap water, not distilled, it might be .001 out.

    The thermometer is accurate.
     
  4. MHB

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    Posted 15/5/19
    What are you testing the thermometer against?
    US-05 will occasionally attenuate surprisingly, but generally around 80-82% is as far as it will go. There has to be a reason why the wort is so fermentable, which mostly comes down to mash temperature.

    A few other possibilities-
    That your hydrometer although accurate at 1.000 might not be so at higher SG's, might be worth making up a sugar water solution and testing at higher gravities (you need accurate scales) 100g sugar and 900g water gives a 10oP or 1.040 solution.
    You might have picked up an infection, there are a few wild yeasts that will hyper attenuate, most of them either taste or smell like shit, so have a smell/taste.

    I really suspect your thermometer or hydrometer are a little less reliable than you think.
    Get a decent lab thermometer if you haven't got one, cost $15-20. every brewer should have one they use as a reference, I mean a glass one, you really cant rely on anything but the most expensive electronic thermometers to be consistent.
    Mark
     

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