New formula from Purolite: Premium Grade 60% anion & 40% cation Resin Mix.A Premium quality indicator mixed bed DI resin for use after the RO process to further reduce your TDS (total dissolved solids) reading. The resin will need replacing when it changes colour from dark green to orange. Here at aquacadabra we believe this is ideal for use in clear housings where the colour change can be observed and where a TDS monitor is not available.All our DI resins are sourced from one of the world’s leading resin manufacturers. This is a high quality long-life resin.Mixed bed resins or mixed bed ion exchange resins are mainly used in the water purification industry for polishing process water to achieve demineralized water quality (such as after a reverse osmosis system). Mixed bed as the name states consists of strong acid cation exchange and strong base anion exchange resin.