Ion exchange resin cartridge for reverse osmosis system platinum line plus - with colour indicator. Aqua Medic RO-resin cartridge is used to remove the last remaining pollutants from RO water such as silicate, nitrate and other ions, 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. The resin changes colour to indicate the efficacy of the filter material. When the conductivity of desalted osmosis water begins to rise again, the resin turns from blue to green and needs to be renewed.Filling capacity for resin: app. 600 ml