Deionization is the removal of mineral ions by using the ion exchange process. Using a mixed bed of anion and cation resins, ions, salts and minerals can be entirely removed from water. If you use a RO membrane, the RO membrane has a direct impact on the life-span of the DI. The RO membrane can remove about 95-99% of TDS (minerals) in your water. When a deionization filter is used after the RO membrane, you can expect almost 100% removal of the TDS. Excellent media for deionization of water for industrial, aquatic, and other water treatment applications. All naturally-occurring water contains dissolved mineral salts. In solution, salts separate into positively-charged cations and negatively-charged anions. Deionization can reduce the amounts of these ions to very low levels through the process of ion exchange. Cations are removed by cation exchange resin. It replaces sodium, calcium, magnesium and other cations with hydrogen ions (H). This exchange produces acids which must be removed or neutralized by anion exchange resin.