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Help please - crazy low OG

Discussion in 'All Grain Brewing' started by Lobby Lobster, 8/8/19.

 

  1. Lobby Lobster

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    Posted 8/8/19
    Greetings,
    I wanted to run something past you people please.
    I put down a 23 litre English Bitter on Sunday with an expected OG of 1.045 (Beersmith).
    This was the second brew in my new Guten and I was happy with the process.
    However to my dismay, my sample after chilling read 1.030.

    I can only put this down to the crush from my LHBS. I didn't even look at the crush to be honest, but I reckon I would have noticed if it wasn't milled at all.
    Anyway, hoping that it was just a dud reading (if that's possible), I put it in the barrel and pitched a starter of Nottingham - which I understand is a pretty fast finisher.
    Four days later I suspect that fermentation is finished.

    65 minute mash at 66.5C
    60 minute boil
    4.2kg Maris Otter
    140g Wheat
    230g Crystal
    20g Roasted Barley

    My question is, should I just ride it out and see, or should I consider throwing some extract in there to beef it up?
    Otherwise, if the OG reading was correct, I'll be looking at an ABV circa 3% and I am guessing that it will also be pretty thin if that's the case.
    Perhaps I have left it too late to add more fermentables?
     
  2. wide eyed and legless

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    Posted 8/8/19
    Did you check the accuracy of your temperature read out against a thermometer on your initial set up?
     
  3. Lobby Lobster

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    Posted 8/8/19
    Hi Weal,
    I didn't but I figure that would make a minimal difference. The sample was room temp or maybe slightly cooler - I do need to get a thermometer that reads lower temps.
    When I have used the Hydrometer Temperature calculator, temp wouldn't seem to account for such large difference.
     
  4. philrob

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    Posted 8/8/19
    How did you measure your OG?

    Did you allow for temperature adjustment either with you hydrometer or your refractometer?

    Also, what brewhouse efficiency do you have your BeerSmith set at?

    How much dead space in your mashtun?

    All of these can have a impact on your reading.

    To be honest, expecting to get an OG of 1.045 from 4.59 kg of malt takes good milling, mashing, draining, and sparging, and for the brewing angels to smile kindly on you.
     
  5. wide eyed and legless

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    Posted 8/8/19
    When you set up your Guten put about 5 litres of water in, could be more, set a mashing temperature say 66 C check the temperature near the probe where the readout on the screen comes from check they are the same if not adjust. I just don't see how it could be so far out especially on your second brew assuming the first one was OK.
     
    devoutharpist likes this.
  6. Lobby Lobster

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    Posted 8/8/19
    Thanks Philrob.
    Hydrometer after cooling so I didn't adjust for temp. Very close to 20 degrees I reckon.
    Setting for Brewhouse Efficiency - good question. I am still getting familiar with some technical things but just checking now and it was set at 72%.
    For the 40 litre Guten what equipment profile should I use?

    Top screen sitting on the grainbed so no dead space.

    You may well be right about being me optimistic about hitting 1.045 with that grainbill, though my first Guten brew was pretty spot on.
    Which is what makes me think the reading was right.

    The thing is, is it too late to add any malt extract - now that fermentation will be pretty much done?
     
    Tony Spalding likes this.
  7. Lobby Lobster

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    Posted 8/8/19
    Good advice. I will definitely do that. Cheers.
     
  8. mongey

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    Posted 8/8/19
    What philrob said. I make 23l batches and with most beers I’d need about 5.5kg of grain to get 23l of 1045 wort. My standard bill is 6kg and that gives me 1050 to 1054 on 23l depending on how it goes on the day

    I don’t have guten , just do biab so my losses
    To true are probably worse than yours.

    That said if I put your bill into my settings at 23l I’d get 1038. So your dad a little low at 1030
     
    Last edited: 8/8/19
  9. Lobby Lobster

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    Posted 9/8/19
    Thanks Mongey. Yeah maybe that’s it. I think I need to revisit the recipe and get a bit more familiar with Beersmith.
    Cheers
     
  10. mongey

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    Posted 9/8/19
    I've been doing AG for a bit over a year now . my expected numbers were all over place until I got to know my system and could predict my trub losses. To get 23l of wort i need to make 27 l . 4 liters is the rubbish that gets thrown , but you still have to take that into account
     
  11. Half-baked

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    Posted 9/8/19
    In answer to the question of will the beer be alright... sounds like you’re gravity is a tad low for an ordinary Bitter, but should be fine.

    I’ve been very happy with beers I’ve made around that range.

    What yeast and what IBUs though?

    Edit: just saw Nottingham. From memory that will leave some residual sugar, helping mouthfeel. That is, assuming your mash was actually 66.5
     
    Last edited: 9/8/19
  12. wide eyed and legless

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    Posted 9/8/19
    On Brewers Friend I get 1,046 @ 75% brew house efficiency for that recipe, on a 23 litre batch, considering your first brew hit the targets I would assume your calculations are out somewhere.
     
  13. ballantynedewolf

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    Posted 10/8/19
    Yeah, you are overly optimistic with that OG off 4.5kg of grain. However your 1.030 is too low for an average efficiency. You'd expect around 1.040 - could you have a 100 error as often experienced by carpenters? That's where you concentrate on the last two digits and get the third last digit wrong eg you're trying to cut 3126mm and you end up cutting 3026 mm. You're bang on with your 26 but it's still too short.
    I don't know what at Guten is, but I do know that in my standard BIAB setup I get much better efficiency from double crushing my grain to 0.66mm. A single crush or the crush from my LHBS costs me 5-10% of efficiency. A fine crush can of course cause stuck sparges, so watch out.
     
  14. Garfield

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    Posted 13/8/19
    I say, go for it. Fermentation will pick back up when you add a new source of fermentable liquor. Boil it up first to sanitize and dump it in.
     

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