In Stock Brands:

Thermax, ResinTech & Purolite

Cation Resin Overview

Cation resin is a negatively charged matrix with exchangeable positive ions (cations). Negatively charged ions are fixed and permanently attached – part of the resin structure. Because the bead is negatively charged only positive ions are attracted or exchanged.

For water treatment purposes cation resin can be purchased in the sodium (Na) or hydrogen (H) forms.  Always confirm the resin is in the sodium (Na) form before loading the tank and installing in a home.  If hydrogen (H) form is used in a residence the pH of the treated water will be very acidic at 2-3 pH.  This is damaging to people and pipes.  Hydrogen form cation is required commercially when deionizing or demineralizing water.

Urbans Aqua stocks Purolite & Thermax cation resin for quick shipment.

Cation Resin Applications

Our rules of thumb when applying these resins:

Installation of an activated carbon filter ahead of the softener to remove the chlorine or chloramine will prolong the life of the resin.

Water Softeners – Hardness Reduction

Sodium (Na+) strong base cation resin is commonly used for household, commercial and industrial water softening applications. According to the Water Quality Association, water hardness in the United States ranges from 1 to 350 grains (gpg) per gallon or 17.1 to 5,985 ppm.   However, most waters range between 3 and 50 gpg.   USGS Water Quality Information

Softening with cation resin is a simple exchange function. The resin bead is negatively charged and attracts positive ions. When supplied in the sodium form (Na+) the resin will exchange sodium ions for hardness ions – calcium and magnesium. The bead is more strongly attracted to these ions and readily exchanges with the sodium. Once the resin is exhausted it is regenerated with a brine solution (NaCl). The brine overwhelms and releases the calcium and magnesium from the bead. The resin is converted back to the sodium form and ready for re-use.

Urbans Aqua stocks:

Water Softeners – Iron & Manganese Removal

The hard water problem is often compounded by contaminants like iron (rust stains) and manganese (black stains). Iron water has a distinctive taste.



Using SST – Shallow Shell Resin for Softening & Iron Removal

How SSTC6000E differs from standard resin.

How it works


Using Fine Mesh Resin for Softening & Iron Removal

Fine mesh resin is also used in residential applications where iron is present.

Lead, Aluminum, and Copper 

Urbans Aqua stocks Purolite & Thermax cation resin for quick shipment.


Strong Acid Cation in the hydrogen form (H+) in combination with strong base anion (SBA) in the hydroxide form (OH), is most often used for demineralization processes such as portable exchange tank (PEDI) operations. In this case, the hydrogen is exchanged for calcium, magnesium and sodium. (For more information please refer to section on demineralization for portable DI exchange operations.)

Some mixed bed resins have black cation and blonde anion.  The first regeneration step of mixed bed is to separate the cation and anion.  Anion which is lighter in weight and color is floated to the top; cation heavier and darker remains on the bottom.  The color difference distinguishes where they separate enabling the regenerator to easily see and move each resin to the appropriate regeneration vessels.

Links to Specifications & Engineering Bulletins:

Resin Cation Engineering Bulletin C100 H Cycle

Resin Cation Engineering Bulletin C100 Sodium Cycle

Resin Cation Engineering Bulletin C100 Sulfuric Acid Regen 08 2013

Resin Cation Overview Brochure Shallow Shell SSTC60

Resin Thermax Tulsion T-42 Na BC N

Resin Thermax Tulsion T-42 Na N

Resin Thermax Tulsion T-52 Na BC N

Resin Thermax Tulsion T-52 Na N

Resin Thermax Tulsion T-240 Na N

ResinTech CN8 Black Cation USA

ResinTech CG8

ResinTech CG10 Cation

Resin Purolite SAC C100E Gel

Resin Purolite SAC C100 Gel Na

Visit our PDF Library for technical specifications and product manuals on cation resins.

Visit our SDS Library for safety data sheets on cation resins.

Urbans Aqua is a stocking wholesaler of Residential & Commercial Water Treatment Equipment and supplies including Thermax, ResinTech & Purolite Ion Exchange Resin; Calgon & Haycarb Activated Carbon; FilterAg Plus; GreensandPlus; Pyrolox Advantage; KDF; Birm; Sand/Gravel; Clack, Fleck & AqMatic valves; Stenner Pumps & Parts. 

We work exclusively with water treatment dealers.