Ask 'Dr. Spa' Q & A Message Board

"Use of the Ozone treatment reduces the need for chlorine, since it lets the ozonation of the water do the oxidation, and leaves the chlorine with only the job of anti-bacterial work."

That is the theory, but IMO ozone in a hot-tub isn't that efficient. Ozone can only affect the molecules it comes in contact with before it off-gasses or combines with something else. If it worked as well as the theory, there would be no need for shock doses to oxidize contaminants. Realistically, ozone might oxidize SOME contaminants and contribute slightly to cleaner appearing/smelling water, but I haven't seen any proof that it reduces the need for regular shock treatments or sanitizer in an appreciable way. Combine that with potential damage to the cover and headrests from off-gassing, and you can understand why it is a controversial subject.