Fiberglass and acrylic tub enclosures are easier to clean and maintain than traditional bath materials such as ceramic tiles; the grout lines bordering the tiles tend to accumulate residue and dirt and become discolored by mold. But there are ground rules to cleaning your fiberglass tub enclosure -- pamper it in the same way you would treat your new car, by using soft rags or sponges, paste or spray wax, and non-abrasive cleaners, and avoiding the use of steel wool or sandpaper. If you clean and maintain your fiberglass or acrylic tub enclosure properly, it should keep its brilliant, reflective factory shine for many years.
Contact your tub enclosure manufacturer to find out what type of cleaner is recommended. Some soaps and cleaners will fade your enclosure's colors, and some contain alkalies that can actually cause cracks. If you can't contact the manufacturer, a mild liquid dish detergent is safe. According to the Home Tips website, it is also safe to use TSP, or trisodium phosphate, as long as it is well-diluted.
Add a water softener if you have hard water; it makes cleaning off mineral deposits much easier.
Rinse all surfaces well with warm water to begin to loosen soap residue. Cleaning your tub enclosure immediately after you've showered will accomplish the same thing; the warmth and humidity will make residue and mineral deposits easier to remove.
Dilute a little liquid dish detergent -- or trisodium phosphate in accordance with label directions -- in a bucket of warm water, and apply the solution with a soft cloth or sponge, rubbing in a circular motion. Do not use a "scrubby" sponge, steel wool, sandpaper, or abrasive cleaners of any kind. Do not use automatic dishwasher detergent.
Make a paste of baking soda and water and scrub with a soft cloth. Use this on hard-to-remove soap scum, stains and mineral deposits.
Clean any glass parts with ammonia.
Rinse the walls and tub completely, and dry well with another soft cloth to prevent spotting.
Spray on furniture wax, or apply automotive wax, to bring back your tub enclosure's original shine, but only on walls and sides, never on the bottom of the tub or any area in which you would stand. Reapply wax every three months to maintain shine, repel dirt, and make cleaning easier.
Buff and polish your enclosure to a high-gloss finish with the third soft cloth.
Call in professionals to refinish your tub if you are unable to restore the shine after cleaning it in this way, or if you have resorted to abrasive cleaners in the past. Once the surface has been roughened, it loses its ability to shine, and can also attract dirt.
Clean your tub enclosure frequently, before it shows residue buildup. You will not have to use harsh products if you keep your tub enclosure consistently clean.