Hey window pros, I have a funny question...how do I get the "scale" or hard water off of my shower. Its probably plastic for all I know..it's the run of the mill stand up shower with cheap metal trim. I squeege after showers but before I bought the house it had this problem. Is there a TOP SECRET chemical to use. I've tried all of teh store bought tub and tile,soap scum cleaners and the "scale" is still there. Can anyone help????