Rust Stains

• Fiberglass bathtubs are generally easy to clean, but homeowners with hard water will have problems. Hard-water stains can accumulate over time and, if not taken care of right away, the stains can be very hard to remove. If your water contains a lot of iron, it's likely you also will see rust stains on a regular basis.
  
  If caught quickly, the hard-water stains can be wiped away with a commercial tub-cleaning solution. When choosing a cleaning product for your tub, read the label to make sure the product is safe for fiberglass. If you need to use an abrasive cleanser to remove stubborn stains, be sure to use a lot of water as you clean--if you do not use sufficient water, the abrasiveness of the cleanser could scratch the fiberglass surface.
  
  No matter what type of cleanser you use, it is important to allow the cleaning solution to soak into the stain before attempting to wipe it away. This will give the cleaning solution time to work and begin to dissolve the stain.
  
  

Mineral Deposits

• Mineral deposits, like those left by hard water, can be gently wiped away using a liquid tub and tile cleanser and a soft, damp rag. It is important to deal with accumulated stains as quickly as possible, because they can set in quickly and become difficult to clean without risking damage to the fiberglass.
  
  When those stains do set in, however, it is important to clean them properly. Use a sponge designed for use on bathroom fixtures to apply a mild cleanser and allow it to sit on the stain for at least a few minutes. The sponge should have a soft sponge on one side and a nonabrasive scrubber on the other side. Once the cleanser has been allowed to soak into the stain, use the scrubber side to work the stain loose, then use warm water to wash the cleanser off.
  
  

Considerations

• One of the best ways to keep your fiberglass tub clean and free of stains is to use the right cleaning materials. In addition to a two-surface sponge, an old toothbrush is an excellent addition to any bathroom cleaning kit. The sponge is good for everyday problems, such as soap scum and dirt, but if you need to get into cracks and crevices, use a soft cloth and an old toothbrush.
  
  In addition to commercial fiberglass cleansers, you can use a solution of baking soda and water or a mild detergent, such as Ivory Liquid. If your water is very hard, it may be worthwhile to invest in a water softener as well.
  
  Cleaning the tub and shower enclosure at least once a week is the best way to keep the stains manageable. The harder your water is, the more frequently you will need to clean your bathroom surfaces.