Re: How do you get the plastic/resin showers or tubs clean?
Look for a product called "Bath Brite." There seem to be several manufacturers that make the same thing under the same name. You can probably find it at a local plumbing supply house; I've never seen it at the Big Box stores (but then I haven't looked for it).
The stuff I have is a pink liquid containing phosphoric acid. Be sure to follow the instructions carefully; apply it a full concentration and let it sit for several minutes without drying out. Then rinse it off.
The "Senior Member" designation under my name doesn't mean I know a lot, it just means I talk a lot.I've been a DIYer since I was 12 (thanks, Dad!). I have read several books on various home improvement topics. I do not have any current code books I can refer to. I was an apprentice plumber for two years.