Aqua Medic Indicator-Resin - 730G Ion exchange resin with colour indicator Mixed bed demineralizer for removing silicate, nitrate and other ions from osmosis water. The special silicate resin helps to limit the growth of diatoms, especially for the aquarium hobby. Used to remove the last remaining pollutants from RO water, by using ion exchange resin as the final stage on a reverse osmosis unit. It reduces the growth of diatom, if silicate levels in tap water are too high.