LiquaGen Color Changing Deionization (DI) Mixed Bed Replacement Inline Filter (2" x 10") This product is great for aquariums, laboratory testing, and other applications where ultra-pure water is necessary. Each filter will have an individual set of 2 clips & 2 elbows for easy installation. This particular green resin is extremely high quality resin compared to the average blue resin. Mixed Bed DI Color Changing Filter In Clear Housing.The anion resin is a Type I strongly basic gel resin with an indicator dye that changes from green to brown as the resin exhausts. The cation component is a strong acid sulfonated polystyrene gel type cation exchange resin.