Message: Thought you would like to read this, it's an article by True Rest of the TrueREST website... Download an independent study of a flotation tank’s water quality. Conclusion: In summary, I am very confident that your Flotation Spas are well protected with regard to their water quality. Threefold protection is provided by standard chemical disinfection with hypochlorite, high turnover filtration and the added effect of the high salt concentration all working together to provide a clean and safe environment for your clientele. Changing the water and magnesium sulfate every 6 to 12 months will also insure an esthetically pleasing experience. Find this article at: http://www.truerest.com/index.php/site/blog/water_quality/