Use a Mr. Clean Magic Eraser moistened with straight Dawn brand liquid dish washing detergent--no water. Then rinse. It was amazing how easily the soap scum washed off my shower using this method.

For two years I struggled to keep our tub and shower clean. My husband works in a job where he gets full of grease. Two years ago when we had the tub and shower put in, it was stressed that the wrong cleaner could void the warranty. We tried what was recommended with no luck. It was just terrible. I was embarrassed for anyone to even see our tub and shower. A year or two ago I purchased Mr. Clean 2 in 1 Eraser. I had never tried it before. Ya know how you buy something and it sits under the kitchen sink forgotten about? Well, It resurfaced as I was cleaning this morning. I thought what the heck... I used it on my fiberglass tub and shower this morning. It was a fricken miracle. I really wish I had taken a before and after picture. It looks like the day they put it in new. Please just try it. You won't be sorry. I promise. It took about 10 minutes and it was in bad shape. Mr. Clean 2 in 1 Eraser. =-)

If you like the tub just fine, and don't welcome the time/trouble and expense of a new tub, I'd suggest trying to just restore it, if you can. As I suspected earlier, it can be restored with just automotive finishing compound and a high speed buffer with a wool pad. From the link below: Q: I have a cultured marble vanity top that is severely scratched and has no shine. Is there anything I can do to restore the finish? Gayle Crawford, Rio Rancho, N. Mex. A: Kevin O'Connor replies: Dan Maki, who has been making, installing, and refinishing cultured marble for nearly 30 years at Cultured Marble Products Ltd., Sacramento, Calif., tells me that the sheen of this material comes from a layer of clear polyester-resin gel coat applied to an opaque layer of fiberglass-reinforced polyester mixed with limestone dust. In his experience, the most common cause of scratched, dull gel coat is cleaners like Ajax or Comet. Cultured marble should only be cleaned with liquids that have no abrasives. Maki says it's fairly easy to bring back the shine and remove shallow scratches using an automotive finishing compound and a high-speed, 1,500- to 2,500-rpm buffer fitted with a wool pad. Rub it in by hand, wait until a haze forms, then buff it off. For deep scratches that don't go all the way through to the fiberglass, wet-sand with the compound and an 800- or 1,000-grit wet-and-dry paper. After sanding, give these spots a good buffing. Once your countertop is back in shape, he recommends shining it occasionally with liquid Gel-Gloss, a polishing wax developed just for cultured marble. +++++++++++++++++++++++++++++++++++++++++++++++++++++ It has no major problems, but has quite a bit of etching and some staining from our hard water that is impossible to remove. Once you have it restored, I'd suggest either cleaning or at least drying the tub after each use, or as often as is possible. Now I'm looking forward to restoring the shower walls to their original sheen. Sue Here is a link that might be useful: This Old House -- Restoring Cultured Marble

I am so glad I found this page......I have well water and the rust is awful even though I use the salt that is suppose to prevent this. Because I haven't been able to find anything to get rid of it...the build up was really bad practically my whole tub and wall was orange. I would clean it even though I could not get rid of it. So I tried the bar keepers friend which I had this whole time under my kitchen sink and boy did it work!!! I am amazed and little annoyed that I had it but never thought to use it. So thank you, thank you, thank you and my tub thanks you!! :) I wish I had taken before and after photos.