The dome on the skylight on the roof over the shower needs to be cleaned and I'm not sure what to use on it to prevent scratching the plastic? What do you use?
Depends on what it's made of....Lexan, Lucite or some other material. For the most part, it is generally a bad idea to use glass cleaning products on plastic as it will deteriorate the plastic and cause scratching and/or fogging. Your best bet is mild soap and water or some other dedicated plastic cleaner/polisher.