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Home , Chloride, Cyanuric acid, Hypochlorite, Liquid bleach, Sodium, Sodium hypochlorite

TECH NOTES

SODIUM , AKA “ ” In other words, By the PHTA Recreational Quality Committee

IN THE SWIMMING pool industry, one gallon of 12.5% hypochlorite a corrosive. As such, a maximum of of the most popularly chosen forms for provides approximately 12.5 ppm of 500 gallons can be stored in a non-fire, sanitizing and superchlorinating water free chlorine per 10,000 gallons of sprinkler-protected room and 1,000 is . Commonly pool water. It takes 10.6 fl. oz of 12.5% gallons in a fire, sprinkler-protected known as “liquid chlorine” or bleach, sodium hypochlorite to get roughly room as maximum exempt quantities. sodium hypochlorite is widely used 1 ppm of free chlorine in 10,000 gallons Quantities beyond this create an “H” in both commercial and residential of pool water. The pH of pool grade Hazardous Occupancy and require swimming pools. Sodium hypochlorite sodium hypochlorite is 13. special fire protection. effectively destroys bacteria and Sodium hypochlorite is Sodium hypochlorite reacts prevents algae in swimming pools. classified as an inorganic sanitizer; in water to create hypochlorous This edition of Tech Notes provides it does not contain cyanuric . information on the characteristics, Sodium hypochlorite is a primary effects and proper application of sanitizer because of its ability to SODIUM HYPOCHLORITE: THE sodium hypochlorite. kill microorganisms, oxidize non- living contaminants like BASIC FACTS WHAT IT IS and swimmers’ waste and provide • Clear liquid with a Sodium hypochlorite (NaOCl), a protective residual in the water. chlorine commonly referred to as “liquid Sodium hypochlorite is non-flammable, • A solution containing chlorine” or , is an non-combustible and non-explosive, water, hypochlorite, sodium created by and containers under 1.3 gallons and a trace amount mixing chlorine gas in water with aretransported as “Limited Quantities” of sodium concentrations of . with no transport hazard classification. • Strong bleaching agent This liquid is manufactured at differing Containers over 1.3 gallons should • Effective sanitizer for most trade percentages. be labeled for transportation as UN1791, pathogens Household bleach for general hazard class 8. Table 1 (on page 79) • Prevents and kills algae cleaning purposes and laundry is shows the ppm of free available chlorine available in concentrations from 1.5% in 10,000 gallons from 1 gallon (8.35 • Oxidizes ammonia and to 6% sodium hypochlorite, by weight. lbs.) of liquid* compared to 1 lbs. per swimmers’ waste Sodium hypochlorite for swimming 10,000 gallons of chlorinating • Provides a measurable pools is usually manufactured at compounds. Sodium hypochlorite is chlorine residual in the water concentrations of 10% or 12.5%. One classified by the Uniform Fire Code as

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AQ05-TechNotes.indd 78 4/7/20 12:11 PM YOUR CONNECTION TO THE acid (HOCl). HOCl is the most the degradation rate. It is important effective sanitizing chlorine species to keep sodium hypochlorite stored in available. HOCl disassociates to OCl- cool, dark and well-ventilated storage INDUSTRY (hypochlorite anion), and the amount areas when possible. Filtered sodium of disassociation is based on pool water hypochlorite has a longer shelf life. pH. At a target pH of 7.5, 50% of the Pool grade U.S. Environmental chlorine exists as HOCl and the other Protection Agency (EPA) registered 50% as OCl-. Since HOCl is the killing sodium hypochlorite has a pH of agent form of chlorine, it is important approximately 13. With its use, the that pool water pH be balanced to degree to which it increases total the most ideal target levels. Because dissolved (TDS) can vary. of its aqueous solution, sodium hypochlorite is immediately available HOW TO USE IT to provide HOCl. It is also an oxidizer Sodium hypochlorite can be applied that removes non-living contamination manually or with use of a positive and is one of the preferred shocking displacement feeder such as a methods, since high doses will not diaphragm, peristaltic pump or a contribute to the increase of venturi feeder system. Manual addition or levels. should be done in the deep end of the Sodium hypochlorite is safe for use pool away from any parts such on all types of pools including plaster, as rails, ladders or rings. Pour colored plaster, aggregates, vinyl liners the liquid very slowly while holding the and fi berglass. container as close to the water surface as possible. Pouring from a high Chlorine Percent ppm FAC position will to undiluted splash type Avail back of product on decks and clothing, which will cause bleaching. It is Cal Hypo 65% 7.8 recommended to wear protective gloves and goggles when applying. Sodium Cal Hypo 70% 8.4 hypochlorite feeder pumps should be set up with the injection point after all equipment to prevent undiluted Cal Hypo 75% 9.0 chemical contact with pumps, fi lters and heaters. Feeder pumps should Tri-Chlor 90% 11.0 be calibrated in accordance with the manufacturer’s specifi cations, and *Sodium 12.5% 12.5 tubing should be checked regularly for Hypo brittleness and leakage. Feeders should be installed to avoid siphoning. WHAT IT DOES Sodium hypochlorite loses strength PRECAUTIONS over time as it is converted to sodium • Sodium hypochlorite is corrosive chloride and water. Large stock and should be stored in a cool, well- quantities should be discouraged. It is ventilated storage area away from better to purchase and store sodium and other chemicals. hypochlorite in smaller quantities that • Care should be taken when applying encourage inventory turnover. The rate to prevent contact with eyes and skin. of decline of sodium hypochlorite’s Use gloves and eye protection such strength is infl uenced by physical and as goggles or a face shield. chemical conditions such as high • Only U.S. EPA registered sodium temperature, exposure to UV light, hypochlorite products should be initial concentration and purity of the used. product. Sunlight and high temperature • Sodium hypochlorite products can speed up the process. Sodium should be used according to the hypochlorite (12.5%) will reach its half- manufacturer’s label instructions. life in approximately 180 days when • The fi ltration/circulation system stored at a temperature of 77 °F/25 °C. should be running when adding PRINT • DIGITAL • SOCIAL At 95 °F/35 °C the half-life is 48 days. products. The presence of metal contaminants • Bathers should not enter the pool aquamagazine.com or impurities in the manufactured until the tested chlorine levels are at product or storage tank will increase 4 ppm or less.

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