I am using spa magic in my hot tub and I can tell you that Spa Magic does remove bacteria from the water. I work for a wastewater treatment plant and we are required to remove pathogens from the effluent before releasing it to the river. We us a fecal coliform test to monitor the cleansing process. I took a sample from my hot tub and tested it using the same process. The results showed no fecal coliforms. I then took a effluent sample and ran the same fecal coliform test with and without treating it with Spa Magic. The effluent without Spa Magic showed 60 colonies of fecal coliform per 100 ml of effluent. The Spa Magic treated effluent at 60 degrees showed only 15 colonies - a 75% reduction. I reperformed the Spa Magic treated effluent test with the sample heated to onver 90 degrees and found no fecal coloform colonies. Email me or visit my website for more detail. I am not a certified lab, but these were personal observations of the product in a test we that we perform weekly at out treatment plant.
Spa Magic has not been approved by the EPA at this point, and therefore cannot use the language "kills bacteria" or claim to be a sanitizer until field studies are completed and approved by the EPA.
Spa Magic is compatable with chlorine and bromine, so that if you need additional sanitizing you can use it. Let be real, if you use your spa a lot and/ or people are getting in dirty, then the Spa Magic may get over loaded and a shock treatment may clear it up quicker. My wife, son and I use our spa abou 3 to 4 days a week and have not used anything other than Spa Magic and some water clarifier to keep our spa clean. The bottom line for me is that I am not sitting in chlorine, nor breathing it and I don't have to test the water for minimun levels of chlorine or shock it after each use. I just look at the water and can see it it needs help.
It is an alternative to chemicals, or at least it will minimize your exposure to the the chemicals, and the chlorine industry does like that.
Bill