For everyday cleaning and maintenance of fiberglass shower units, use non-abrasive liquid cleaners. Wash down the floors and walls of your unit with warm water and these detergents, using a soft cloth to remove any remaining spots.
For stains and other stubborn spots on the fiberglass shower, a paste may be made of a moderately abrasive powdered cleanser. Spread the paste on the stains and allow it to sit for 5 to 10 minutes. Scrub the stain with a soft brush and rinse the area with warm water after the spot has been removed.
For hard water deposits, white vinegar or a lime removing product may be used to help remove the stains.
To restore shine to a dulled fiberglass finish, a product like Gel-Gloss can be used. These products are designed specifically for use on bathroom finishes like fiberglass and cultured marble. Most of these products are applied to the dry shower surround with a cloth, allowed to dry and buffed off like a wax.
If your fiberglass shower is cracked, punctured or the finish is otherwise deeply marred, it is possible to patch and repair the unit rather than replacing it. Many manufacturers of fiberglass bath products make repair kits for their products. These will involve applying a paste-like patch to the affected area, allowing it to dry, sanding it to make it more even with the surface around it and covering the patch with a protective gloss coating to further allow it to blend with the shower unit.