it is not bad per se, just a waste of the electricity consider the benefit. However, some do swear that they make a big difference in FO system and disease control and water quality. YMMV.
Funny you mention that. I have done some reading already and I noticed that some people don't recommend ozone for rookie aquarists. I will do more research and if i do decide to go with a UV sterilizer first I'll let ya know!