wow, very interesting experiment, I wish I knew what was going on. why do you doubt your ppm reading? what device are you using to measure it with? isnt it possible your ppm readings were correct? perhaps the ozone broke the silver up into smaller and smaller particles?
i did this same experiment in reverse. i ozonated some water for about 45 minutes then made CS with it. the ozone seemed to speed up the process greatly. it took only about 10 or 15 minutes to make the CS whereas normally it takes 45 or 50. i have no idea how or what it worked that way.