I used ozone for about a year or so in my 90 gallon tank. I bought a 50mg unit which is pretty undersized for my tank (I believe 250 or something is "more appropriate". At the time I wasn't using it to max out the bioload in my tank nor was I using it against disease. I was looking for something that would make the water crystal clear. At approximately 27mg it got the job done. Even at full dose for the unit I couldn't do any damage to my tank. I did have it hooked up to an ozone monitor (which to be honest I never fully understood, it had a low alarm but no high one). My tank hovered around 430 or so for ORP and I had to clean the probe weekly or it would give faulty readings.
Ozone will reduce your skimmate regardless of the amount you use. Ozone breaks down organic particles in the water, increasing clarity, however those organic particles are no longer removed by the skimmer because a good portion of them simply aren't there anymore, they've been oxidized. With the use of ozone, my skimmate was reduced to about 50% of the normal production rate. The clarity of the water was unbelieveable.
Some reading:
Ozone and the Reef Aquarium Part I by Randy Holmes-Farley
Ozone and the Reef Aquarium Part II: Equipment and Safety by Randy Holmes-Farley
Ozone and the Reef Aquarium Part III: Changes in a Reef Aquarium Upon Initiating Ozone by Randy Holmes-Farley