The FILTERSORB® CT is the combination FILTERSORB® SP3 and FILTERSORB® SPA is viable treatment for water with hardness over 15 grains, well water or permanent hardness over 250 mg of (Ca + Mg + SiO2 + SO4) is typically over 60 % of the total anions.

Anion Scale Prevention in Hard water

The two types of FILTERSORB® units are SP3 scale prevention and SPA anion scale prevention.
SP3 units prevent cationic scale based on positively charged ions such as calcium and magnesium and with nucleation it changes them into CaCO3 crystals.
SPA units prevent scale based on negatively charged ions such as sulfates, silicates and phosphates (Calcium phosphate).
FILTERSORB® CT units prevent scale of both cations and anions, both positively and negatively charged ions.

Treatment of Cations and Anions Total hardness

Due to differences between temporary hardness and permanent hardness that make up the total hardness in water, we have combined FILTERSORB® SP3 and FILTERSORB® SPA in a 50 : 50 mix. This configuration is described as FILTERSORB® CT. The 50% SP3 was selected to treat for temporary hardness based on carbonate hardness and the 50% SPA was selected to treat for permanent hardness which is mostly based on sulfates and silicates.

Did you know there is a difference between temporary and permanent scale?  One easy way to determine the difference is to place a piece of the scale with an acid. Household vinegar can be used for this simple test.  If it dissolves, this is temporary scale.  If not, it is permanent scale.  


If new metal (copper, brass, etc.) piping or fittings are used BEFORE Filtersorb media, there MUST BE a 60 day bypass period for the metal to passivate (cure). pH must be above 7.0.

Failure to do so will significantly shorten the life of the media.

This will be evident by the media color changing from white to blue or green.

* * Pressure needs to be under 80 PSI to ensure the media has enough contact time and does not clog at the top of the filter * *

CT Brochure