Do I need to use any other chemicals in my hot tub with a sanitation (saltwater system) besides salt? What happens if I put other chemicals in the hot tub?

It depends on where you get your water from. Sanitation creates chlorine from the salt added to the water. It does not affect other parameters. Always test the water with test strips. If you need to balance the pH, alkalinity or hardness of the water, add other chemicals or consult a pool chemical supplier. Adding other chemicals to the water will not affect the salt in the spa. However, always avoid essential oils, fragrances, perfumes and mineral products, which could damage the spa motor.