One method is to make a paste of equal parts baking soda and hydrogen peroxide, apply it to the stained area, and let it sit for a few hours before scrubbing it off. You can also try using a commercial stain remover specifically designed for fiberglass surfaces. Always test a small, inconspicuous area first to ensure it doesn't damage the tub.
I use baking soda to clean my acrylic tub/shower. It gets out a multitude of stains. Maybe it will work on this
I've been using white vinegar.
try two things....one buy soft scrub with bleach and try using it to bleach out the color of the tub. if that doesnt work...try using kaboom. i swear thay gets anything out of the tub. ether or, let it soak into the color to try and help your problem.
A paste of baking soda and vinger.
Baking soda is perfectly safe to clean just about anything.
bleach
A good basic cleaner is baking soda made into a paste. Scrub the stain with the paste then rinse. Spraying with vinegar before rinsing can help lift extra dirt from the surface. Do not use ammonia, it can damage the finish. [I found this out when I mixed ammonia and soap to remove a copper stain on a tub]
If you have city water (decent city water that is) a fiberglass unit with typical warranties of approx. 6 years, will do you just fine. Acrylic is best for places with well water and have typical warranties of about 10 years. The difference is that acrylic fiberglass is solid throughout, whereas what is known as a fiberglass unit has what is essentially a spray coating of acrylic on the surface. Thus the solid acrylic fiberglass units are "tougher" It is recommended for either unit to use something like car wax (on the walls ONLY, never the floor, unless you use non-slip mats) to protect the unit, at least once a month.
To remove toilet bowl cleaner stains from the tub, you will need hot water and a sturdy brush. Get the brush wet and use elbow grease to clean the stain.
hair and soap scum which is grease
If you drop a hair dryer in a bath tub, you will electrocute anything in it.