[bertoni]

I think you're interested in using a plenum or a deep sand bed, from what I understand. There's no need to feed calcium acetate to run a substrate for denitrification. I would use normal sand, because light shining through the substrate will encourage photosynthesis, which will add oxygen. "Aerobic anoxic" is a bit of a contradiction, since aerobic metabolism refers to the consumption of oxygen. Photosynthetic organisms produce oxygen, and they will grow given light and nutrients.

Setting ozone to a specific ORP can be quite dangerous, as tanks vary in the ORP levels naturally. What is the purpose of the ozone? If it's being used to break down organics, I would set the controller for it to a bit above the level seen without ozone, and work from there.