Replace after 3,000 gallons (3-4 months) or when the color indicator turns black. Reverse the filter monthly for best results. Use with T3 Source Hand-Held Model No. 73303 (sold separately). Tourmaline produces negative ions that reduce water cluster size, which improves filtration and helps PH balance the water. Improves hair health and beauty. Enhances the color retention and vibrancy of processed hair. Helps skin to be less dry, retain more moisture and look healthier. Copper, Zinc, Calcium work together to convert and remove chlorine.