Blichmann black grease on fermenator

[bnachtig]

Anyone ever heard of or seen black grease looking material post fermentation inside the fermenter? Cleaned very well prior to use. It won't come off and has stained the stainless steel. Any help would be awesome!

 

[The_Bishop]

Pictures would help in the diagnosis.

 

[VladOfTrub]

I use Blichmann fermenters and noticed the same thing, but not in every ferment. This might be purely coincidental or may have something to do with it. I notice it when using hops that have a wide span between alpha and beta, when using high filtered water not RO or when I am too lazy to dump trub. The same exact brewing method, temps, yeast and grain are used in every batch. It seems to form at the location where the krausen touches the dome. I use a blow off and the gunk collects around the blow off connection, on the dome and inside of the corny cap. Once, the ferment slows down, I transfer to a secondary. The secondary is clear of black gunk. I'm not sure if the problem is related to the Blichmann fermenter, but more so, to a chemical reaction caused by water chemistry, excess trub, hop acid, yeast and alcohol, working on trub and hop resin. It is hard to clean off, for sure. It has changed the finish on the stainless corny cap, which hasn't posed a problem with product quality. The stuff is a ****** to get out of the corny cap. Hot PBW doesn't touch the stuff at first, but it seems to allow it to flake off after soaking a few days, then drying. Now, here's something that might be related to the issue. I only brew lager and pils, using tri decoction method. In ferments where the black gunk was noticable. After lagering and aging, the beer had an "earthy" taste. I noticed the same taste in Heiniken cans, once in a while. The taste isn't offensive, but not desired.