Some of the products that are good for cleaning a fiberglass tub include non-abrasive cleaners such as liquid laundry soap or hand dishwashing liquid. Bathroom cleaners and all-purpose household cleaners are also good for fiberglass, as long as they contain no abrasive ingredients.
A fiberglass tub can also be cleaned with baking soda by making a paste with water and baking soda, then applying it to the surface of the tub. The paste should be rubbed into the surface of the tub gently with a soft brush or sponge and then rinsed away. It is also safe to use a soft-scrub product on fiberglass as long as it is applied gently with no steel wool or other scouring pads used.