Biostone Filter used in Alkablue water ionizers. Contains layers of Tourmaline and Coral Calcium inside an carbon block filter. This unique filter has been created by Jupiter Science specifically for their water ionizers. It helps naturally ionize and filter water before it enters ionization chamber. Tourmaline crystal is known to be a beautiful, semi-precious gem. Now as a mineral it also became a focus of scientific research. One of the reasons is that infrared Tourmaline is the only mineral on earth to show permanent electricity. It was found in Japan, that even if broken in pieces, a positive and negative electrodes never disappeared. Tourmaline in your filter is used to transform water into mild alkaline water.