Originally Posted by SCSInet
Ozone oxygen doped with an extra ion, making it O-3 instead of O-2. It's highly toxic and will kill anything it comes into contact with in sufficient concentration in the water column, such as algae, parasites, etc. It's injected directly into the protein skimmer (through the air intake or venturi hose) to cause it to contact the water.
Toxic as it may be, ozone is highly unstable in water and will dissipate very rapidly once it leaves the skimmer, so if properly applied, there is very little risk to the inhabitants. What it does do is scrub the water incredibly clean and clear.
Ozone cannot be bottled, or stored, it must be generated as it's needed. For this you need an ozone generator (ozonizer). Lots of companies make them, Red Sea is one of the more popular ones.
You can use an ozonizer by itself and just be really careful at the rate setting (how much ozone to inject), but the preferred method is to pair it up with an ORP (Oxygen Redox Potential) controller which can turn the ozone unit off and on and maintain proper (and safe) levels in the tank.
Ozone is, IMO, an option for advanced aquarists who are willing to invest the relatively large amount of money it takes to implement it properly. I'd start with carbon, increase your water change frequency, reduce feeding frequency, and change your light bulbs if they are over [1 year, Halides or T5s / 6 mo, all other fluorescent) to start out.
I agree with SCSInet, but I don't and would never advocate running an ozonizer without some type of controller......Doing that would be totally crazy IMO.......The controller is vital, because it monitors your ORP level, and tells the ozonizer when to turn on and off depending on the levels you preset.....I seen a post the other day about someone saying to put it on a timer, and that again is wrong.....You don't know when your levels are going to change, and as pointed out Ozone can be lethal if adminstered wrong and carelessly.......With a timer your level could be high and the timer turns it on and it continues to run and you basically sterilize your system........If you have a ORP reading of 385 and up you should back off the ozone all together, because your to the point of sterilization.....400 is deadly......