DI Resin with Color Change Indicator, one FULL cartridge refill. -Specially formulated mixed bed resin is Ideal for aquarium application. -Reduces TDS to ZERO - Place at final stage in your RO system - Purple color turns to neutral when resin bed needs changing - 600g(1.3lbs) fills standard DI canister(packed tight for best efficiency!) -Vacuum sealed in mylar bags, the day it arrives with guaranteed freshness and quality. Lewatit® NM 65 is a premium grade, gel type, high capacity, color indication mixed ion exchange resin prepared with a 1:1 chemically equivalent ratio of cation to anion resin. Lewatit® NM 65 is a mixture of gel type cation exchange resin and a standard cross-linked gel type anion exchange resin. The mixed resin is prepared from component resins which have been manufactured with the highest degree of purity and conversion to the H+ / OH form.