I have a large homemade skimmer that I use with ozone. It has been running for over 30 years and so far I have not seen any problems. Randy would know if it is helping anything as I have never ran the tank without oxone so I don't know.
I do not use carbon but the outflow from my skimmer enters a 5' long algae trough where any residual ozone would disapate but I don't think there is any residual ozone.
Ozone has a strong smell and you would detect it right away. It gives me an instant headache. I can put my nose right up to the skimmer and I will not smell anything so I know all the ozone is being used up in the skimmer and none of it is going into the air.
If a hose comes off or for some reason the skimmer stops, then I can smell it right away.
I like using ozone because I have used it for so many years and my tank with all the SPS and LPS are thriving with very few water changes.
Inside my skimmer with the ozone I can see amphipods running all over the place so it does not seem to bother them at all. Also the algae trough where the skimmer is pumping water to is home to many amphipods and uncountable brittle stars.
I feel that the ozone is being depleted in the lower portions of my 5' skimmer because I feel these creatures would not be living while being bathed in ozone.
In the clear acrylic part of this skimmer I can see amphipods.