A single-bed  demineralizer ...

A single-bed  demineralizer  contains either  cation  or  anion  resin beads. In most cases, there are two, single-bed  ion  exchangers in series; the  first  is a  cation  bed and the second is an  anion  bed. Impurities in plant water are replaced with hydrogen ions in the  cation  bed and hydroxyl ions in the  anion  bed.  You always run through strong acid resin (action removal) first.  No need to do the above.  Cation>Anion>Mixed bed.  Rinses and back washes are imperative for all to get the proper reveal without slippage or channeling.  Read up on this basic configuration for a demin system.  You can take loading off and probably save money with a zeolite softener upstream to remove hardness.  This will also prevent calcium sulfate formation in your action bed.  It happens when you have a poor regeneration sequence and your purge of the rinse is incomplete.  Test your beds for conductivity before you put them in service after the regeneration to ensure no acid is left.  Using hydrochloric helps, but you vessels need to be lined or otherwise protected from corrosion by HCl.  These are the basics, but you can fine tune with a dilution study to get your optimum testing standards to move forward in each step until it is second nature.  This will also lay the ground work for potential fouling challenges later.  Dilution study once a year and resin clean every 24 months minimum.  Enjoy the carnage.  Fun subject though.  Best, Sean