Stuck Dunkelweizen

[Snailof2Cities]

Hi, everyone - bit of a newbie question, but I have c.20l batch of Dunkelweizen stuck at a FG of 1.018 (OG 1.046) - and I am pretty sure that this is because I added only 1 (instead of 2) Wyeast 3638 smack packs. I misread the recipe, though would add that the Wyeast pack said 1 pack was suitable for a 19l brew). I had no issues with the first week of fermentation (so think temperatures were all ok, oxygenation was fine) and everything was going great..... until it stalled. I have tried rousing the yeast and increased the temperature (which collectively got it from 1.022 to 1.018). It hasn't moved from here in about 3 days. So my question- if I add another smack pack of the same (activated, liquid) yeast - what do you think my chances are of getting down to somewhere near my (1.012) FG? Will the alcohol kill the new yeast? Any tips? Thanks in advance!

 

[Alex4mula]

On my 73 brews one pack of anything always worked fine for a beer of that ABV even for lagers. So I think your problem was not using double. Will another pack lower FG? Maybe.

 

[AlexKay]

If you underpitch and then ferment too hot, you’ll produce lots of esters ... which for a Dunkelweizen is what you want. So I don’t necessarily see a down side to raising the temperature again. What was your original temperature, and what is it now?

 

[Steveruch]

All-grain or extract?

 

[Snailof2Cities]

thank you - it was all-grain. The original fermentation temp was 19/20c (66/68F), which I raised to 22/23c (71.5/73F). Raise again?

 

[AlexKay]

I'd probably try 24 C/75 F. I wouldn't think rousing would help: it's a weizen yeast, so it's not going to drop out anyway. I also wouldn't expect adding yeast to help.

It's at 60% attenuation, so it's not too far off, and depending on how much crystal and roasted malt you used, 1.012 might have been a bit of a stretch anyway.

Did the hydrometer sample taste sweet?

Are you going to bottle or keg it?

 

[Snailof2Cities]

Hey, Alex - got it - turning the heat up as we speak. The sample is quite sweet (not unpleasant, and definitely tastes like a 'weak' dunkelweizen) - intention is to bottle it... when I'm happy it's safe.... you think the alcohol in there would kill another yeast pack, or worth swinging the bat if it's not going to ruin it? thanks again

 

[Snailof2Cities]

oh - used 3.5kgs of wheat malt (6.6lbs), 1.5kgs (3.3lbs) of Munich, 250g caramunich (0.5lbs), 75g (0.2lbs) carafe special (and 100g of rice husks). Mashed-in at 68c (154f) for 55mins, and out at 76c (170f) for 10mins.

 

[VikeMan]

oh - used 3.5kgs of wheat malt (6.6lbs), 1.5kgs (3.3lbs) of Munich, 250g caramunich (0.5lbs), 75g (0.2lbs) carafe special (and 100g of rice husks). Mashed-in at 68c (154f) for 55mins, and out at 76c (170f) for 10mins.

With your grain bill, mash temp and length, yeast strain, and OG of 1.046, I'd expect this to get down to about 1.014. Your 1.018 is not all that far off. If it's actually stable at 1.018, I would suspect the yeast have simply run out of fermentables.

you think the alcohol in there would kill another yeast pack, or worth swinging the bat if it's not going to ruin it?

The alcohol wouldn't kill a new yeast pitch. If you want, go ahead and try it. But personally I suspect it won't change anything, again if that 1.018 is stable.

 

[Snailof2Cities]

appreciate this - thank you