could be burn from foliar spraying, or if you are overnuting them they will burn like that. Ph test your solution, make sure your only using 1/4 nutes, add a couple drops of superthrive and they should be ok. That is not bug damage. are you foliar spraying? Try lowering your concentration. I had similar issues just using too much superthrive.
Ozone damage typically found near the generator. Although a rare problem, symptoms generally appear as a Mg deficiency, but the symptoms are localized to immediately around the generator.