Aquatic Life Color Changing Deionization ResinAquatic Life's Nuclear Grade Color Changing Mixed Bed Resin physically changes colors as it becomes exhausted, allowing you to monitor the consumption of the DI resin and know when to change it out. If you use a TDS meter on your RO RODI system we still recommend color changing resin as it will let you know when to monitor your TDS meter before the total dissolved solids in your filtered water start to increase. Our color changing DI resin is packed