That was a very interesting reply, cdurkin100,
yes i use ozone to both polish the water in which i use the dosage of 10mg/100 liters so i'm currently running 50mg/hr in my 550 liter fish only system, (well invert, as it has a lot of live rock), and without a redox controller i would say its at a very safe level, ( 3 years plus) and i could even use more, and have used more, theres no smell of ozone in the system, and livestock are healthy
I also have used it in a protein skimmer and even with impressive results, i rather run it seperately, as my v2skim 800 has never so much as collected anything when ozone was running on it, so now i have this ozonizer hooked up to a hi blow 20, feeding ozone into a separate compartment in the sump and being diffused through a couple of 12 inch airstones.
Now i have done that, the protein skimmer does collect waste, but never enough as to even half fill the cup, (my tank is lightly stocked).
I've never believed in using high amounts of ozone to kill of parasitic infection or whitespot, i'm a preventative kind of guy and if there was any need, i would take out my fish and treat them seperately, in vats with filtration and other requirements set up. Though i DO believe that its good to use to keep possible infections and out breaks of whitespot due to stress to a minimum in ANY tank. Besides, the time and level needed to make a real difference may actually harm livestock unintentionally.
I've never actually used an ozonizer personally when it was set on a timer, i've always used them on continually, even in my late reef tank, i had to break down due to lack of time and budget. I always though that theres was no point in having it on half the time or less, just like people who say they run there u.v sterilizers for 6 or 12 hours per day, and people who do the same to their protein skimmers.
I agree fully on your veiw on its effects on humans, yes high amounts can cause health problems, but too much of everything could harm or kill us, but when i had my reef tank and ultra small fish only system running side by side in my bedroom, i used ozone on both of them and during that 3 years, no dangers of health emerged to me whatsoever!