Spa Marvel&reg; Cleanser 8 oz The perfect way to clean your spa & hot tub before using Spa Marvel Water Treatment. Spa Marvel Cleanser is a fast acting proprietary cleanser that penetrates deep inside your spas plumbing and equipment, removing organic, mineral and chemical contaminants. Prolongs the life of spa and hot tub equipment and heater element. Works great in whirlpool/jetted bathtubs.