Okay, go buy yourself some GLISTEN ( it's primarily used to keep dishwashers clean, but it works on other stuff too ! ), pour about 1/2 a packet into your poddy, let it stand for a an hour or more, and you'll get those nasty stains out. :-)
I've never heard of that. I use a pumice stone. Next time I go to the store, I'l look for it, thanks.