With the industry-wide shortage of trichlor tablets, more pool professionals are left with little choice but to switch customers to alternative sanitizers, especially liquid chlorine and calcium hypochlorite. Since it involves volatile and corrosive chemicals, changing sanitizing methods comes with a host of concerns, from proper dosing and pH levels to safe application, transportation and storage. It’s a complex subject, but there are some basic things pool professionals should know.
“One of the first things to consider when making the switch from trichlor to liquid [chlorine] or cal-hypo is the level of the cyanuric acid (CYA),” says Terry Arko, product training and content manager at HASA Pool, manufacturer and distributor of pool and spa water treatment products. “Many who have used trichlor tablets as a primary sanitizer may not realize the increased amount of CYA that comes from the tablets themselves.”
He notes that two trichlor tablets in 10,000 gallons increases the CYA by 6 ppm. Fifty pounds of tabs used over a season can raise the CYA by 224 ppm. “High levels of CYA will make chlorine less effective,” he explains. “If you don’t do some draining and dilution to bring the CYA level down, you will have to use a lot more liquid or cal-hypo.”
Cal-hypo is available in a variety of forms, primarily fast dissolving granular; fast dissolving tablets and briquettes; and slow dissolving tablets. Ellen Meyer, product safety and governmental affairs manager with Sigura, a supplier of water treatment products, notes that slow dissolving cal-hypo tablets are a more direct replacement for trichlor tabs than other types of cal-hypo.
“The slow dissolving cal-hypo tablets were designed to dissolve as slow, or slower, than a trichlor tab, so they are a good way to provide a constant chlorine residual throughout the pool in between service visits,” she says. “The cal-hypo tablets have the advantage that they do not contain any cyanuric acid and will not contribute to overstabilization, algae growth and chlorine demand, or slow chlorine efficacy.”
On the subject of switching from trichlor tabs, Eric Knight, vice president of business development with Orenda Technologies, a manufacturer of specialty chemicals in Fairview, Texas, makes many of the same points about CYA and other issues related to water chemistry. He adds that liquid chlorine has the disadvantage of degrading over time and does not last nearly as long as trichlor or cal-hypo in storage.
“You don’t want to hoard it if you’re not going to be using it within a few weeks, because it will degrade and lose strength,” Knight says. “It gets weaker and weaker by the day. Don’t leave it out in the sun all day either. Store it in the shade, in a well-ventilated area.”
The safe handling of pool chemicals, which are inherently hazardous, is of even greater concern than the issue of water chemistry.
“There is a real danger if someone puts cal-hypo tablets in a trichlor floater or feeder,” Arko says. “This will cause an explosion. Cal-hypo is a [National Fire Protection Association] class 3 oxidizer, which means it will combust and become flammable when it comes into contact with any type of organic product. This includes even things like rainwater, soda pop, oil or grease, perspiration and also trichlor.”
Meyer is emphatic on the importance of pool professionals learning the safe handling of pool chemicals.
“All chlorine products have the potential to form chlorine gas, which is toxic and corrosive,” she says. “Chlorine gas can be formed as the products decompose or if the products are contaminated. Chlorine gas will be formed if any of the products are mixed with acid. That is why acid should never be stored above any chlorine product.”
She adds that all chlorine products should be stored in cool, dry and well-ventilated areas out of direct sunlight and away from children. They should also not be contaminated with water, with other chlorine products, other pool products or any other contamination.
Transporting these chemicals safely is another concern.
“Liquids should never be transported in single loose bottles that can tip and spill,” Arko says. “Liquid should be transported in secondary containment plastic carrying cases or crates that are free of any holes or cracks. Liquid chlorine products should be kept separate from liquid muriatic acid as much as possible. Never stack acid above chlorine or vice versa. Keep dry chemicals separate from liquids when transporting as well.”
“The best way to prevent leaks is to keep chemicals in their original packaging,” Meyer says. She cites the Code of Federal Regulations (CFR), which includes regulations for transporting hazardous materials, and the “materials of trade exceptions,” which provide maximum quantities that may be transported. She says that the regulations include requirements as to how service technicians separate incompatible materials in their trucks. “When using liquid bleach, consideration should also be given to the disposal of the empty bottles and boxes.”
On the complex and important subject of pool chemical safety, Meyer recommends pool service companies have current staff and new hires watch a 14-minute video prepared by the Chlorine Chemistry Council at Chlorine.org/Pool-Chemical-Safety. “Each pool product has unique safety concerns,” Meyer says. “We want to ensure that service techs using these products are aware of the potential hazards and know how to handle these chemicals safely.”