chemical-free water treatment

It started a couple years ago:  More and more often, I was meeting clients who wanted great pools and spas that involved no chemical enhancement - just the water itself. These were generally people who had studied up.  They had rejected dichlor and trichlor and were opposed to any kind of cyanurate presence.  They'd considered saltwater pools until they figured out that chlorine was part of the package.  They'd looked at ozone and were concerned