Mixing Resins – How to Avoid Calcium Carbonate Fouling of Drain Lines

By: Michael Urbans

Mixing cation & anion resin in a single tank.

This blog is about mixing sodium form cation and chloride form anion resins in a single tank.  Not mixed bed resin, which is hydrogen (H) form cation and hydroxide (OH) form anion.

These are the resins we’re discussing:

When these resins are in separate tanks the cation is ahead the anion tank.  The hardness minerals are removed before the water goes through the anion resin.  Both are regenerated with sodium chloride (NaCl) – salt.  Sodium (Na) exchanges with hardness minerals; chloride (Cl) exchanges with anions – sulfate, nitrate, etc.  Use of this common regenerant (salt) creates the opportunity to combine cation and anion in one tank.  Anion resin is lighter and rests at the top of the resin bed; cation is beneath it.

Hazard Warning

Calcium Carbonate may form if the water hardness is above 6-8 grains.

How to avoid the problem.

How to repair.

Want to hear more?  Check out our podcast It’s Your Water.