Cleans and purifies the water..

Here is the info I mentioned. I have read this several places but this quote is from Reef Aquarium 3.

"Small organic and inorganic particles often have a similar electrostatic charge.....Using small amounts of ozone, the charges of some of these particles can be changed causing them to clump together with unlike charged particles in a process known as microflocculation. These larger particles are more susceptible to removal by protein skimming, however, if too much ozone is added, then all the particles are altered, no unlike charges remain, and microflocculation does not occur. At higher levels, the ozone will also begin to break apart the carbon bonds of the long chain polar molecules attached to the air bubbles within the skimmer, causing them to break apart and go back into solution. This is why a protein skimmer stops producing foam when too much ozone is added."


Basically if used correctly and I do mean correctly it is a great aid to a skimmer and better then a UV sterilizer.