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Help! Slow/Stuck Fermentation!

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  • Help! Slow/Stuck Fermentation!

    Help!
    I have a Belgian Golden Strong Ale fermenting miserably slow and I'm trying to get it to ferment out.
    O.G. 20.2 Plato, pitched 18.6 million cells/ml of WLP570 on 7/11/09 with 98% viability. Oxygenated heavier than normal and fermentation started within 24hrs and continued strong for 6 days. I set my jackets for 28C but the temperature never rose above 27C.

    After 15 days, 9.4 Plato @ 22C and signs of fermentation practically stopped. I repitched with WLP001 and recirculated the tank through the racking port. Temp increased to 24C and signs of slow fermentation were evident.

    That was almost 2 weeks ago (total 1 month in fermenter) and the gravity is still only 7.2 Plato and now @ 23C. That's only 64% attenuation..!

    The beer actually tastes pretty good, but is too sweet. I made a 5% Belgian Blonde with this yeast from the lab pitch and pitched the Golden from that batch about 2 days after it reached terminal gravity with 86% att.

    The curious thing is that I also gave a friend 5 gals of of the same yeasted wort at the end of brew day and it fermented out completely.

    Any advice is greatly appreciated!

  • #2
    The main possibility is lack of oxygen. Some yeast strains are extremely greedy for oxygen. At that gravity we are using pure oxygen to achieve 18 - 20 ppm in one hit. Alternatively aerate at low level for a few hours after 6 to 12 hours to get some more oxygen in. Another method if using two (or more)brews is to start off the first brew with air saturated wort, and add the second brew after 6 to 12 hours with air supersaturated wort

    Other possibilities include lack of yeast nutrients, particularly zinc as sulphate or chloride, calcium, soluble nitrogen, or far less likely, something has simply gone wrong in the mash and the temperature was far too high.

    You are highly unlikely to get this going again and be able to obtain the correct flavour by adding more yeast, air / oxygen and repitching as you are likely to suffer diacetyl. Probably better brewing a new batch altogether on it own, or getting a new brew fermenting vigorously and adding the existing brew to it. You may well need to split the present stuck brew between two or more new brews
    dick

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    • #3
      I had a similar situation with WL saison II. Did a 24P Quad pitched and O2'ed the hell out of it. It took off fast and quit at 15P. Added WLP01 and O2. Got it to right around where your at 7.5-8P and it quit again. I roused the yeast with CO2 in the bottom but nothing. Finally I added another dose of WLP01 and lo and behold it started slowly cranking again and crawled down to 4P where I finally chilled it a bit to 50F because I didnt want it to dry out anymore. Dick is right about the yeast being greedy for O2. Once it goes anaerobic it creeps. I say if you have the time and your getting some action, let it go and it will probably finish out. Add some more 01 but no O2 at this point. Extra yeast cant hurt, and it certainly jump started mine even though I'd done it before. I'd have to double check, but my whole ferment took about 7-8 weeks.
      Big Willey
      "You are what you is." FZ

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      • #4
        Aha!

        Thanks guys.
        I used yeastex in the boil for nutrients and used a new Pilsner malt that I've never tried, Global Pils. I got unusually low efficiency with it- possibly a clue there?

        I didn't add any O2 when I repitched for fear of oxidizing the alcohols but did try and blow CO2 into the bottom a few days ago to re-rouse the yeast. It's still bubbling veeeeeeery slowly.

        I don't really have the option of re-brewing it, so, I'm just gonna let it go and see what happens. After another 2 weeks I'll reassess. Thanks for the input!

        BTW, is there any general guideline as to what gravity range you should over oxygenate? Above 18P? How about adding more O2 the 2nd day?
        I have had issues with high gravity brewing a few times and can't seem to find general guidelines.

        -fingers crossed

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        • #5
          Adding O2 the second day surely wont hurt. Like I said I added it a week later at 15P and the beer tastes good, no oxidized flavors. Two other tricks you could try 1) Add some dextrose to the tank. My buddy at a very large micro told me this one. He says sometimes giving the yeast some simple sugars will jump start them and get them to keep going after its gone. 2) as a last resort add some enzymes to break down everything to simple sugars. This almost always works but be careful or the beer will go very dry. Add very little.
          Big Willey
          "You are what you is." FZ

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          • #6
            We used to do a 25 / 26 P brew, and had to aerate very slowly after, I think 12 hours after collection, again, if I remember correctly until the PG was about 10 P, otherwise it stopped dead. I do know it was a delicate balance between over aerating and getting low esters and not getting to the target gravity. But of course the O2 required depends so much on yeast strain. I'm afraid it will be trial and error to a large extent for the first few brews
            dick

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