Questions for the 2019 AGM, page-6

A possible answer to your query. Ozone treatment and anything else that is used to purify pool water that is not using chlorine ,is unable to be be tested for a purification level. In public or semi public pool situations , standards require a reading of 2 parts per mill free available chlorine to be safe swimming condition. If they use something else to kill bugs , this will reduce the amount of chlorine needed to achieve the standard
In private pools , of course , there are no Govt regulations saying you can't swim in your own pool , but maybe , they have decided a few hurdles exist to hold up marketing and promoting a product that has no general acceptance . Just a thought