Captor® NSF Calcium Thiosulfate Solution

Many treatment plants today are looking to use inherently safer chemicals to reduce hazards to health and the environment. One of these chemicals is Captor, which has become an attractive alternative to traditional water treatment chemicals used for dechlorination and ozone quenching.

Captor is now solving a number of traditional problems for water and wastewater treatment plant operators. Tank and line heating are generally not needed, and the product presents no problem with off-gassing. Captor offers several advantages over the use of traditional treatment chemicals, including:
  • It is a non-hazardous solution
  • Maintains a low freezing point
  • No potential SO2 exposure
In addition, the use of Captor places less stress on the environment as compared to other chemicals. Captor is not an oxygen scavenger and consequently does not reduce dissolved oxygen; its near-neutral pH hardly affects the pH value of the water.


Active Ingredient [w/v % Calcium Thiosulfate] 30% Min
Active Ingredient [w/w % Calcium Thiosulfate] 24% Min
pH [Full Strength] 6.5-8.0
Specific Gravity 1.20-1.32
Weight per US Gallon 10-11 lbs/gal
Crystallization Temperature 24-28°F (-4.4 to -2.2°C)

Captor is manufactured as an aqueous solution according to NSF Standard 60 at several sites here in the US. It is available in nonreturnable drums or totes. Store totes, drums and small containers out of direct sunlight at moderate temperatures. Materials of construction suitable for storing and handling Captor include stainless steel, aluminum, fiberglass, poly tanks or lined carbon steel.

Captor is considered non-hazardous with NFPA ratings: 0–0–0 for health, flammability, and reactivity. The vapor space over the solution is largely water (no off-gassing) and bulk storage is generally permitted without secondary containment. Avoid mixing Captor with acids. Observe all safety precautions shown on the Material Safety Data Sheet.

Captor is super concentrated and typically used for high chlorine concentration application but can be used for all types. Figuring out how much Captor to use is simple. We have developed a dosing calculator below that you can use for any and all of your projects.

The dosage formula is as follows:

Gallons of Captor Needed = Volume of Water (Gallons) x PPM Chlorine Concentration / 200,000
Go to Super Dechlorination Kits page.

Volume of Water (Gallons)

Chlorine Concentration (ppm)

Gallons of CAPTOR Needed*

* Values generated are should only be used for estimation. Actual results may vary.





5 Gallon Drum
Discounts on orders of 10 or more



15 Gallon Drum
Discounts on orders of 13 or more



30 Gallon Drum
Discounts on orders of 13 or more



55 Gallon Drum, 4 drums/pallet
Discounts on orders of 4 or more



275 Gallon Tote on a Caged Skid


QTY XMT10240

HDPE Drum Pump

Formula: CaS2O3
Formula Weight 152.2
Calcium Thiosulfate 30% w/v
pH 6.5 to 7.5
Specific Gravity 1.240
Appearance Clear Solution
Physical Properties 10.34 lbs/gal (193 gal/ton)
Solubility Soluble in water
Domestic Shipping DOT Proper Shipping Name :Not Regulated
Information DOT Hazard Class: Not Regulated
DOT ID Number: Not Regulated
Authorized Shipping DOT Rail-Bulk: Calcium Thiosulfate Solution
Document Description DOT Truck-Bulk: Calcium Thiosulfate Solution
Containers Tank Cars: General Purpose, DOT Approved
Tank Trucks: General Purpose, DOT Approved

IMPORTANT: The information presented herein, while not guaranteed, was prepared by technical personnel and is true and accurate to the best of our knowledge. No warranty or guarantee, express or implied, is made regarding performance, stability or otherwise. The information is not intended to be all-inclusive as the manner and conditions of use, handling, storage and other factors may involve other or additional safety or performance considerations. While our technical personnel will be happy to respond to questions regarding safe handling and use procedures, safe handling and use remains the responsibility of the customer. No suggestions for use are intended as, and nothing herein shall be construed as, a recommendation to infringe any existing patents or to violate any Federal, state or local laws.