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WECO XRT390 Whole House Salt-Free Water Conditioning System

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  • Premium 3-stage whole house filter system designed and assembled in the USA, effectively reduces chemicals and scale throughout the entire house. Enhances the longevity of various water-using appliances, including tankless water heaters, reverse osmosis water filter systems, ice machines, coffee machines, and water coolers.
  • Stage one: USA-made 5 micron nominal pleated filter removes rust and sediment from water, ensuring purity.
  • Stage two: American-made compressed coconut shell activated carbon block filters chlorine and VOCs for superior water filtration.
  • Stage three: FILTERSORB® SP3 media cartridge uses Nucleation Assisted Crystallization (NAC) to prevent scale buildup by converting calcium and magnesium into harmless microcrystals.
  • Four in/out gauges monitor pressure differentials across all filter stages, providing comprehensive oversight. Italian-made high-flow 1-inch FNPT single-mold reinforced polypropylene three-stage filter housing enhances durability.

What is Filtersorb SP3?

FILTERSORB®SP3 is the result of extensive research work along with its undisputable success in the market, worldwide since 2005.

Watch®‘s core motivation for developing this product was to find an alternative to conventional ion exchange based water softeners, reverse osmosis or other chemical based systems that prevent scale.

Recent restrictions placed upon the above mentioned technology lead to an environment friendly, cost effective solution for hard water, Watch®‘s FILTERSORB®SP3. FILTERSORB®SP3 completely takes care of the primary cause of scale forming cations viz. Ca2+ and Mg2+

Working Principle

When the hard water under goes nucleation in the pressure vessel, the calcium bicarbonate Ca(HCO3)2 is transformed into aragonite form of calcium carbonate CaCO3 crystals. These crystals are formed through decomposition and crystallization process, forming very stable harmless crystals.

The following equation describes the reaction that occurs inside the pressure vessel when flow over grains of nucleation.

Ca(HCO3)2→ CaCO3 + CO2 + H2O

The name fragment “SP (Scale Prevention) 3“ is to indicate this unique transformation of water hardness Ca(HCO3)2 into 3 components viz.

CaCO3 (micro-crystals)      CO2 (colloid) and      H2O (pure)

In the pressure vessel, the equilibrium of carbonate species in water is changed, assisted by the driving force of stable crystal formation and therefore the reaction is pushed to the right →. With this technology, as long as CO2 is being removed the soluble Ca(HCO3)2 converts into insoluble calcium carbonate (CaCO3) crystals

The calcium carbonate crystals grow steadily. They are very stable and cannot dissolve (incapable of forming scale) in the water.

Glass grains crystallization sites provide increased nucleation sites for the formation of submicron sized CaCO3 crystals. Hence this amazing process is called NUCLEATION ASSISTED CRYSTALLIZATION or NAC in short.

Physical Characteristics
Appearance White / opaque solid granules
Composition modified ceramic beads
Bulk density SI
780 kg/m3
48.7 lb / ft3
Particle size SI 0.55 – 0.75 mm
Mesh size US 20 x 35
Moisture content 10 – 25 %
Operational parameters & water impurities
Flow direction Up Flow
operating time
5 – 80 °C
41 – 176 °F
ph range 6.5 – 9.5
Hardness, max. SI
1338 ppm (mg/l)
75 gpg
Salinity, max 35000 ppm (mg/l)
Iron, max. 0.5 ppm (mg/l) * * FILTERSORB® SP3 is able to remove Iron from water with very high efficiency
Manganese, max 0.05 ppm (mg/l)
Free chlorine, max 3 ppm (mg/l)
Copper, max. 1.3 ppm (mg/l)
Oil free
Hydrogen sulfide free
Do not use where water is microbiologically unsafe or with water of unknown quality without adequate disinfection before or after the unit. System must be maintained according to manufacturer‘s instructions. Pre-treatment for sediment, Iron, Hydrogen Sulfide, Manganese, hydrocarbons and Copper may be required depending on conditions.Install systems in new facilities with copper pipe after six weeks of water use.


FILTERSORB® SP3 has proven itself in a variety of applications as an alternative to ion exchange softening or other conventional water treatment methods. The maintenance-free characteristics make it especially suited for Foodservice and Commercial applications where equipment maintenance is often overlooked. FILTERSORB® SP3 treated water preserves the essential minerals Calcium and Magnesium, making the water most healthiest drink available.

Home appliances

Faucets, water pipes, shower heads, shower cabins, toilets. All beverage systems, kitchen machines, dish washers, ice cubes, compact washers.

Major appliances

Central heating, air conditioners, water heaters, air humidifiers, coffee and tea makers, solar heating systems, water coolers.


Hot water boilers, central heating boilers, combo boilers, catering water boilers, boilers and pool heaters, commercial water heaters, industrial hot water boilers

Cooling towers

Closed circuit cooling towers, open circuit cooling towers, concrete cooling towers, cross flow cooling towers

Industrial appliances

Winery, Car Washing, Diary Processing, Food & Beverages, Injection Moulding, Irrigation, Nurseries, Reverse Osmosis pre-treatment etc.

Other applications

Irrigation, Swimming pools and SPA, Dairy Processing, Winery and, Beverages, Planting and Gardening, Automobile Washing, Hotel, Restaurants and Institutions.

Working Principle
No TDS change

As FILTERSORB® SP3 does not remove or add anything to the water. As no ion-exchange chemistry is used, the TDS of the water remains unchanged before and after the treatment.

No pH change

pH value of the water remains the same. This factor makes the treated water suitable for almost any use where corrosion is concerned.

Minerals Preserved

FILTERSORB® SP3 does not add sodium or any chemicals to the water. It simply reserves the Calcium and Magnesium contents of water, making the treated water arguably the healthiest mineral water available. Both Calcium and Magnesium are quintessential for nervous systems and muscles functionalities. They are indispensable parts in the cell chemistry of the plants and most of the life forms on earth.


Not only does FILTERSORB® SP3 prevent scale formation, but it also helps to remove the previously formed scales. During the flow some of the micro-bubbles are losing a small amount of CO2, which diffuses rapidly in water and interact with surface scale, especially in closed spaces (pipes, boilers, etc). As a result, the scale which is already present on these surfaces is removed slowly.

Biocidal effect

The NAC process creates the conditions that water dissolved CO2 agglomerate to form micro-bubbles. These CO2 bubbles actively destroy bacterial membranes acting as a biocide. So along with the scale prevention FILTERSORB® SP3 also helps to prevent Biofouling.

Special Information

FILTERSORB® SP3 has good capacity to absorb Iron, Copper, Manganese, Lead, Zinc etc. Hence in high concentration presence of these contaminants the FILTERSORB® SP3 beads may change color and come to an end of the media life. From studies it‘s also possible that the media might change color due to dye leaching from the container tank made of polyethylene.

In case of any strange color change of the FILTERSORB® SP3 media beads or the treated water is noticed, please contact us with detailed water analysis


  • FILTERSORB®SP3 is certified under ANSI/NSF 61 from WQA, USA
  • FILTERSORB®SP3 is BS 6920:2000 (British Standard, UK) certified.
  • FILTERSORB®SP3 is tested to meet MSZ 448-36:1985 standard (Hungary).
  • FILTERSORB®SP3 is certified from Department of Environmental Hygiene (Poland).
  • FILTERSORB®SP3 Tested to meet WRAS (Water Regulations Advisory Scheme, British Standard, UK) Standard of Product Quality and High temperature
More Information
UPC 670087222062
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Can this system measure my house water pressure?

By Richard
on January 21, 2024
  • Certainly, the XRT390 inlet pressure gauge will display the water pressure sourced from your house plumbing, while the outlet pressure gauge will indicate the pressure after the water has been treated and exited the filter system.
    By Matt
    on January 21, 2024

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Does it need a drain connection?

By Andrew
on January 6, 2024
  • XRT390 is a water-efficient system that does not generate waste water, eliminating the need for a drain connection.

    By Matt
    on January 6, 2024

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What is the flow rate?

By Andrew
on January 6, 2024
  • The manufacturer of Filtersorb SP3 antiscalant media recommends a flow rate of 4 gallons per minute. However, the system is capable of handling a peak flow of 7 gallons per minute, specifically for chlorine reduction.
    By Matt
    on January 6, 2024

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How long does the filters last?

By Andrew
on January 6, 2024
  • Replace the 5MPLWCT4520 sediment filter every 6-12 months or when the pressure differential reaches 10-12 PSI, whichever occurs first.

    The ACB-4520-5 carbon block filter has a chlorine reduction capacity for 50,000 gallons or 12 months, whichever comes first.

    Change the FSB-2045 antiscalant cartridge every 24 months or when the pressure differential reaches 10-12 PSI, whichever comes first.
    By Matt
    on January 6, 2024

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Are the nucleated CaCO3 crystals removed by the 5 micron sediment filter? I understand micro crystals from TAC systems still allow film formation on glasses and silverware. While this is easy to remove , it nonetheless occurs.

By dave
on November 7, 2023
  • It's important to note that the system is specifically designed to safeguard plumbing from the impacts of hard water and does not eliminate CaCO3 from the water to prevent hard water spots.
    By Matt
    on January 6, 2024

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