Quote:
Originally Posted by Dentoid  ...
As for the safety, according to Bob Fenner @ WetWebMedia, the small ozone units made for the hobby do not produce enough ozone to be dangerous to you or your fish and all the ozone produced and run through the skimmer is all used up before it exit into the tank. ... |
I don't happen to agree with Bob Fenner. In the "olden days" when ozone use was a lot more common, and skimmers were driven with air stones, I accidentally killed off all my fish with the over use of ozone. This was partly because the contact time in skimmers of that vintage was much higher.
See also this link about ozone pollution -
U.S. Study Finds There Is No Safe Level for Ozone - US Department of State
As you can see, it doesn't take much ozone to cause a problem. The use of carbon is cheep insurance.