Prevents Scale, Staining, and Calcium Build-Up on Surfaces ClearRay® Stain & Scale protects your spa from metal and mineral impurities found in spa water by suspending and inhibiting stain and scale causing minerals.The water used to fill your spa may contain high amounts of metal that can stain or discolor your spa's surface. The presence of minerals can cause oxidizing and scaling on the shell's surface and erosion of the heater element. Directions for Use: On startup or initial fill, add 16 ounces for up to 500 gallons of water while it is being filledand before any sanitizer is added. When you add water to your spa, you may need to maintain your ClearRay® Stain & Scale levels. Add 1 oz. per 100 gallons of ClearRay® Stain & Scale to hot tub water while the pump is running. Allow the water to recirculate overnight or until the water is clear. This will help to control any mineral staining and will help to protect the heating element from corrosion. If staining continues due to excessive mineral levels in water, increase dosage. NOTE: Draining and cleaning of spa or hot tub is recommended every 3 months.