When chlorine dissolves in water, the percent chlorine as HOCl and OCl- is determined by the pH. Bleach has a pH of around 12 due to the presence of NaOH, so the solution consists of mainly hypochlorite (OCl-) with very little hypochlorous acid (HOCl) present. (See graph.) HOCl is the primary reactive species (the species that kills pathogens) in sodium hypochlorite bleach, NaOCl, solution. Because there is a low concentration of HOCl in bleach, it must be used at high concentrations to be effective.
High concentrations of bleach have long been trusted to be very effective against harmful pathogens, but these high concentrations are harmful to humans and can damage surfaces. TK60 is a 200ppm solution of water and hypochlorous acid, HOCl. TK60 is also chlorine dissolved in water, but at a pH of 3.75-5.5, where HOCl is the dominant species and there is very little OCl- present. This is why TK60 is so effective against bacteria, viruses, and spores at such low ppm concentrations; you are producing the part of bleach that does the killing, so high concentrations are not necessary to get the job done.
One reason HOCl is more effective against pathogens vs OCl- is due to the neutral charge of HOCl. Typically, cell walls have a slight negative charge, which makes it very difficult for negatively charged OCl- to penetrate cell walls (opposite charges attract, like repels like). HOCl, being a neutral species, has less of an issue with the negative charge on the cell wall, so it passes through more easily, destroying the cell of the pathogen that gets in its way. HOCl is also a stronger oxidizer compared to OCl-, which aids in the destruction of pathogens due to oxidative stress. Another advantage of HOCl, is that it does not interact with any of the cell’s protoplasm, which makes it impossible for pathogens to create resistant strains against it.