I've noticed a whitish film building up on the interior of my new stainless fermentor (and also a bit on the dip tubes of my corny kegs).
Neither oxyclean nor PBW seems to be effective at removing it. I can just barely scrape a bit off using my fingernail.
If I run my finger down the inside of the fermentor, I can feel exactly where it starts (it has kind of a rough, almost non-slip surface feel to it).
Is this beer stone? If so, what is a good way to remove it?
I feel like bar keeper's friend would probably work, but I've only ever used it to clean the outside of kegs and the inside of kettles. Is it safe to use on the inside of a fermentor with non-scratch (blue) scrub pad?