After 20 years of fermenting in glass carboys, I recently dove in and bought a Blichmann Fermenator. I Scrubbed it according to the docs that came with it, and then gave it my usual BTF soak and air dry before brewing with it.
The first batch had a pretty godawful metallic or.. I don't really know how to classify it... harsh smell after 1 week in primary. Same recipe I had just brewed successfully a month prior, sans the funky smell. After a week I dumped trub, dry hopped for 2 weeks of secondary. The smell remained. It's not a spoilage smell-- after sharing it with other homebrew geeks we all agree it's not an infection smell. It's pretty astringent, slightly metallic, maybe somewhat chemical. Though my mash was only at 150º so I shouldn't have extracted tannins to give astringency. The beer tastes fine, not great.
Anyway, when I popped the lid after 3 weeks, there was a layer of black scum on the sides of the fermenator just above the krausen ring. Oily. Not green or white like most mold. The beer itself looked like... well... beer.
I ended up dumping the batch and brewing again. This new batch has remnants of that smell, but not quite as bad. It was a long road to get here, but here's the question, at long last:
is there something I need to know about fermenting in steel? Does this funky smell blow off once it gets to glass or gets carbonated? Or was I blowing it off before by racking/oxygenating and just never got to smell my beer at this stage?