I bought one of those polish machines too, but i went for the 14000mg machine, it works fine for small rooms,it's very much the same a much more expensive machines, some say they dont produce as high an ozone output as they claim, but there is an easy way to check, just look at the voltage of the transformers inside, if they are 10,000v that will be 10,000mg of ozone, mine is 14000v so 14000mg of ozone, the worst thing about most ozone machines is the tiny little computer fan that is used by them. mine has plenty of output and after a few uses my rubber feet on the machine perished and fell off! at least it proves it works I suppose, as ozone destroys rubber after a time.lol
We also use much bigger output machines(42000mg) that we have adapted to force ozone into carpets that have urine or other nasties in them!and ozone is the strongest cleaning agent known(acts over 3000times faster than chlorine), so use the proper breathing gear if you have to enter the room when running!
all the best
John.