How do you take suntan lotion stain off of a fiberglass shower?

After many applications of spray lotion by a family member our shower is now a rusty color on the walls and floor. It is not from the water. It is definitely from the residue of the lotion. Will my shower ever be white again?

Try using baking soda on a wet sponge and scrub the tub - do this several times. Then rinse the tub with hot water and vinegar.
Good Luck