The Optimum Focus detox footbath uses a similar process that is medically approved called Peritoneal Dialysis which uses to move cellular waste from the body.
When Himalayan salt added to the footbath water, immediately break up to form negative ions and positive ions. The Optimizer water array is design to maximize the production of negative ions. The negative charged ions will be bound with a positive charged elements (toxins in the body have positive charge). And then it pushes toxins into blood stream, where body eliminates them through elimination system. 
The water at the end of the session will have colors due to oxidation, cellular body waste and toxins/impurities in the water. Human Cells have been viewed under a darkfield microscope that shows improvement after just 1 treatment. It shows the human cells as rounded and free-floating, showing oxygenation and hydration has occurred.