Kim Komando, America's Digital Goddess
 

How to Clean Fiberglass Showers and Tubs

Heat white vinegar until it is hot, but not too hot to pour into a spray bottle and work with. Spray it on the shower and tub heavily. Wait 10-15 minutes and then moisten a scrubbing-type sponge with more of the vinegar and scrub down the shower, using additional heated vinegar as necessary. Rinse well and dry.