Ten Gallons of Wort -- Two five gallon batches -- both stuck at 1.020

I have a schwarzbier and a a black IPA both made from the same wort (O.G. 1.055, Black IPA raised up to 1.062 by steeping crystal malt). The schwarz was fermented with the dry Weihenstephan strain, and the BIPA with Nottingham.

Both beers are now stuck between 1.020 and 1.021 after 21 days each. The schwarz was removed from my chest freezer to start a diacetyl rest, but never moved any further. I roused the yeast by shaking the keg in which is was fermenting (figuring there is no oxygen in there). This was a couple days ago, and I am waiting another few days before I check it. I just checked the BIPA, and it has not moved in a week.

Any ideas here? I figure the first answers would be that my wort was not as fermentable as I thought it was. It was mashed at 150 for 90 minutes. Next I figure my thermometer may be off, but I am pretty sure that is not the case either ( I just checked it against another for good measure ).

I was planning on racking the schawarz onto the Nottingham when it finished, but now that it is not moving either, I am really at a loss. Any explanations other than the ones above would really help me cope here.

:rockin:

It's possible that it's just finished. Maybe raise the temp a bit and rouse the yeast with a light swirl then check again in a couple days.

I can't speak to the explanation of why it stuck there but if you have some Amylase enzyme you may be able to take it down a few points.

Just racked the BIPA ( still stuck) onto a 1214 yeast cake. We'll see how it goes.

that is the only explanation I can think of ( the grist: 10 lbs Munich II 9 lbs Pilsener 1 lb Carafa III (an additional pound in sparge) 1 lb carapils).

Would the amount of carafa contribute to a larger than normal amount of unfermentables? Bothe beers have spent additional time on a 1214 yeast cake, neither moved, but they both taste okay -- the BIPA is on tap now and is not overly sweet like I thought it would be even though it only attenuated in the 60s. The lager is still green, even less attenuated, but does not taste overly sweet either.

I could blame it on a bad o.g. Reading, but the two readings were done at separate times.

Has anyone else seen a large amount of carafa do this to your fermentation? When it is all done, I am likely to have two good beers, but this is still a head- scratchedr.