Description: Mineral stones are a combination of maifan stones and bio-ceramic energy balls. Mineral stones are the 7th stage of the Santevia gravity system. They constantly release easily absorbable minerals into the water, including calcium, magnesium, phosphorus and potassium. When removed from its source of alkalinity, the pH of water decreases. Mineral stones maintain the alkalinity of your water, while adding trace elements. Mimics the effect of rocks that line cool mountain streams for great tasting water. Filter life: up to 2 years.