I think one of the issues of the design is that the air is used to puch the water out of the reactor and the variations in pressure unless regulated makes it for a somehow unstable operation so the floats and vent line.
In my engineering days I used to work at air destillation cryogenic plants, the destillation column work with liquid/gas interface. It is nothing else than a sophisticated vertical column with perforated trays where very cold air is injected at about the middle of the column and liquid Nitrogen is injected at the top. as the liquid travels down trough the orifices of the trays it exchanges with the ascending air which prevents the liquid to completely drain out of the trays providing a very effective exchange. As the air ascend it is stipped from the Oxigen which liquifies and as the air ascends Nitrogen remins, by the time it reaches the top it is pure Nitrogen and by the time the liquid reaches the bottom it is liquid Oxygen.
Using the same principle I think a column of perforated trays where the water is injected from the top and the air is injected from the bottom can also be very effective and can be operated at whatever pressure you desire just by restricting the air output from the column balancing pressure and flow to keep a layer of water in each tray so the ascending air has to bubble trough the falling water. By the time the water reaches the bottom it has been saturated with Oxygen and the Ozone has had enough retention time to react with whatever chemicals are carried by the water. The taller the column and the larger the number of trays the more effective the exchange. The larger the holes and column diameter the higher the water flow that could be handled, of course more air will be required.
So there you are.
By the way, I found pre-perforated PVC pates taht shall be easy to cut round and just pile up inside an acrylic tube (recomend 1/4" thickness) or sch 40 PVC with caps top and buttom and that's it.
One of these days when I stay home long enough I will try it.
