Bob Lowry on Which Pool Chlorine Is Actually Strongest

Show Notes

“Trichlor is 90% available chlorine, so it must be the strongest” sounds logical until you follow the math all the way through. We sit down with Bob Lowry to untangle the biggest chlorine strength myth in pool care, breaking down what “available chlorine” actually means, why the industry compares everything to chlorine gas, and how a percentage on a bucket can mislead even experienced pool owners and pool service pros.

We talk through the practical way to think about dosing: pounds of chlorine delivered to the water. That’s where liquid chlorine (sodium hypochlorite) often surprises people, because a gallon of 12.5% can deliver about a pound of available chlorine even though the label number looks “small.” We also unpack why trichlor’s label ends up doubled when compared to the chlorine gas standard, and how competing terms like weight percent, trade percent, and liquid concentration keep the marketplace confusing.

From there, we zoom out to the real-world tradeoffs that matter more than bragging rights: every chlorine type adds something to the pool. Liquid chlorine adds salt over time, cal hypo adds calcium, and stabilized chlorines like dichlor and trichlor add cyanuric acid. We also get blunt about saltwater chlorine generators: they do make chlorine, along with sodium hydroxide and hydrogen gas, which ties directly to rising pH, corrosion risk when water evaporates and leaves salt behind, and the need for proper bonding to avoid electrolysis problems. If you’ve ever relied on “boost” mode to shock, we explain why that’s not the same as rapid superchlorination.

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We clear up the myth that a higher percentage on the label automatically means a stronger pool sanitizer. We walk through how “available chlorine” is calculated, why chlorine gas is the comparison standard, and what salt systems really produce in your water.
• why liquid chlorine can deliver about a pound of chlorine per gallon
• how trichlor’s “available chlorine” number is based on a comparison standard
• weight percent vs trade percent and why labels confuse buyers
• what chlorine gas actually does in water and why the standard persists
• the hidden add-ons from each chlorine type: salt, calcium, cyanuric acid
• why saltwater generators are chlorine generators and what else they create
• output limits, voltage/current issues, and salt level problems that reduce chlorine production
• corrosion, evaporation salt residue, and why proper bonding matters
• why SWGs raise pH and why boost mode is not a true shock

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