Try doing some searches, this was just recently discussed at length. Personally I have little knowledge on the subject. And no it doesn't run out... It generates the O3
Correct, it converts atmospheric O2 into O3 with UV light, the same way our sun does it in our upper atmosphere.
O3 is a very unstable isotope of oxogen, it has 3 O atoms bonded in one molecule as opposed to the oxogen we breath which has 2. As a result, the ozone will rather readily give up one of it’s O atoms to become the more stable form of O2 which is what we breath. You really doen’t even have to ask it for that 3rd atom, just bump it and it will drop it on you. This is a prosess known as oxidation. It’s how rust is formed. GFO, granular ferric oxide is pelitized rust. Iron that has been oxidized and the powder pressed into grains so the don’t float all over your tank.
It also oxidizes many other compounds, for instance nitrate (NO2) into nitrate (NO3). It will oxidize almost any organic in our tanks and many of the plastics and metals near our tanks.
Don’t be too conserned about that, it has a very short half-life. The reason you have to generate O3 and can’t just buy a bottle of it like Co2 is that it would have a shelf life of just a few minutes.
GAC (carbon) doesn’t have any special “ozone destroying powers” what it does have is a tremendous amount of surface area, or lots of places for O3 to bump into and release that 3rd atom. Assuming you have the olfactory acuity to smell ozone and you can stick your head under your stand and not smell ozone, you don’t have anything to worry about.
Really the most overlooked, and cumbersome aspect of O3 in fish tank is the air dryer. Depending on design, an O3 genorator will lose about 1/2 of it’s effectiveness with humid air. Periodically bakeing and rotating dryer beads is a task onto itself.
