My new house has a fiberglass tub in one bathroom and a fiberglass jet tub in the other. I am in Fl, it is nothing but sand around here... Which results in a grey, streaky residue around the sides of the tub. I have not found anything that really cleans it well..... You can't really scrub too hard... Or it scratches....what the heck do you clean these things with! It's driving me crazy, it never looks clean and as far as I'm concerned who ever made these things should be shot!.... Ok, not really ...but at least hung up by their toes..... :/.