Your hot tub has a fiberglass reinforced, acrylic shell. Stains and dirt generally will not adhere to your hot tub’s surface. A soft cloth or sponge should easily remove most dirt. Most household chemicals are harmful to your hot tub’s shell. It is important that you do not use any abrasive cleaners or strong chemicals. Sodium bicarbonate (baking soda) or vinegar can also be used for minor surface cleaning. Always thoroughly rinse off any spa shell-cleaning agent with fresh water.