303® Fabric Guard for Outdoor Fabric Hot Tub & Spa Covers - 16 fl.oz Metal and Scale Control you can find them here

you can find them here

and will still require chlorine

Leisure Time® Bright & Clear Water Clarifier for Hot Tubs and Spas neutralizes and removes particles to create clear spa water

Replace the silver ion cartridge every 4 months

303® Fabric Guard for Outdoor Fabric Hot Tub & Spa Covers - 16 fl.oz Metal and Scale Control you can find them here303 Fabric Guard for Outdoor Fabrics is a fabric protector spray that strengthens and restores lost water repellency for your outdoor fabrics, including fabric hot tub covers. Safe for outdoor fabric hot tub covers such as WeatherPro (Hot Spring, Caldera, FreeFlows Spas, Endless Pools) and WeatherGuard (Tropic Seas Spas). Safe for outdoor synthetic and natural fibers Protects against water based stains Does not alter fabric color, feel, flammability