Does saltwater stain stainless steel sinks?

[Lydia]

Thanks for all the input!

I'm posting some pics - I just scrubbed my sink with an SOS, and these definitely won't come off.

I don't think I've ever taken pics of my sink before :P

Thanks for all your input - any guesses now that you've seen the pics? It's not rust, it's not calcium... It IS a 30 year old sink, so maybe its warranty ran out about the time I got saltwater tanks?