I have been using a CAP OZN-JR Ozone Generator
http://www.plantlightinghydroponics.com/cap-oznjr-ozone-generator-up-to-1000-cubic-ft-p-2066.html for over a year now and I love it. I use it in a 8x8 flower room that's sealed with a large active air carbon filter with a 6" fan recirculating the air in the room and it kills any odors the filter doesn't catch. Now I'm using it in my veg room without a carbon filter and it there is no smell at all.
This small generator has not caused any problems at all to my plants but I'm not sure it's the same with the larger ones.