I have a whirlpool tub that used to leave a water line every time it was used. I had to clean it with a liquid chemical that smelled terrible, because the plastic surface would scratch if anything abrasive was used.
Since installing the Vortex Water Revitalizer, I have not used the chemical or scrubbed the tub at all. Now I simply rinse it with a handheld shower and dry the flat surfaces with a sponge, and it shines like a new penny.
The tub manufacturer advises owners to clean the internal piping with a bleach and automatic dishwasher soap solution. This solution is circulated through the pump to kill bacteria that live inside the wet pipes. When cleaned this way, the bacteria appear as small black slime particles in the circulating water. Normally this cleaning has to be done once a month to maintain sanitary conditions.
I performed this cleaning the day before the Vortex Water Revitalizer was installed and then repeated it again one month later. After using the Vortex Water Revitalizer water, there were no black slime particles present at all.
To be sure, I even unscrewed the jets and checked the inside of the pipes by hand. They were completely clean. Before installing the Vortex Water Revitalizer I could always feel slime inside the pipes, and it would turn my fingers black.