Some additional pluses in using ozone.
1. The odor in the air from the waste collected in the skimmer is gone. You no longer have the periodic fishy smell around your system.
2. Heavens for bid, but we have often read about someones complete system going belly up, due to some sort of crash; ie; pump goes down, power goes out, etc.
Often they start out saying only a few fish or coral died. Then in less than a day all hell breaks lose and they loose nearly everything, from the death spiral that can happen. Something dies in the tank, that is not found our quickly removed, and the aerobic microbe population blooms. The water becomes cloudy and they consume all of the oxygen, causing even more things to die.
If you are feeding ozone, the chance of the microbe population in the water blooming is greatly reduced. Ozone will kill bacteria in the water and keep it from getting cloudy with oxygen consuming bacteria. So, I believe the chance of the oxygern consuming bacteria death spiral being stopped is greatly enchanced if you use ozone. Hopefully I will never have to find out.
As someone already said, yes you can overdose and kill with ozone, but the chance are slime with the small size aquarium ozone units, and assuming you don't put one sized for a 500 g tank on a 50 g tank. The fact is you can kill with every type of additive you put in your tank, including salt, if you over dose.
I use a Red Sea Aqua Zone Plus 100 ozonator with a built in controller. I love it. I set it at 350 amd max feed rate 50, it runs itself, turning off and on, maintaining 350 mv. Even if it didn't turn off no damage would be done. I feed it into my PM skimmer. MY whole system, including the skimmer are all run off of one pump. I use a single Dolphin Amp 3000.
The water quality is without question better using ozone. The water gets crystal clear. The coral has never looked better. If the level starts to drop below 350 and takes too long to recover, more than a half day. I then know I need to do something to improve my water quality, like a water change. The ORP meter is a great barometer.
The ORP meter alone is worth the cost now that I have used it. ORP reading is the best indicator I have for what is happening in my tank. It is also a good prophylactic to keep from spreading disease in the tank.
If your discharge is into a sump any ozone carry over is quickly dissipated. Running it through carbon isn't a bad idea as insurance. but, ozone oxidizes so quickly it is difficult for it to remain in the water more than seconds with the small amount of ozone put out by the system.
Ozone feed has now become more of a back up system for CPW(controlled plenum wasting), because CPW now maintains my ORP over 350mv, and the ozone is normally not running.
