Ozone is a great oxidizer but due to its volatile nature only lasts a few seconds so there is no residual protection requiring you to add chlorine or bromine. Ozone generators for spas are very low output and will quickly degrade over time requiring frequent replacement in order to realize the benefits.

Ozone is a great suppliment and will help you use less chlorine or bromine. An ozonator with good output will oxidze the copper and silver in mineral cartridges, causing them to be trapped in the filter.