Drain your pool according to manufacturer's instructions. Allow the Pebble Sheen surface to dry completely to kill stain-causing mold or mildew spores present.
Pour 1/2 gallon of warm water into a bucket. Add 1/2 gallon of white vinegar.
Soak a sponge in the vinegar solution. Wipe down the Pebble Sheen surface to remove stains left by mold or mineral deposits.
Dip an old toothbrush in the diluted vinegar. Sprinkle baking soda over the bristles.
Scrub stains that are difficult to remove with the safe abrasive. Rinse the toothbrush as needed. Continue to scrub with the toothbrush and sponge to remove all the stains.
Rinse the Pebble Sheen surface by wiping it with a damp cloth. Dry the surface with clean cloths before allowing it to air-dry the remainder of the way.