Ozone is added via ozone generator... not a recommended tool at this point. Disturbing or aggitating the surface of the water will increase gas exchange, thus increasing O2. Reverse daylight refers to a refugium(an attatched water vessel in which macro algae and critters not able to grow in the display tank are allowed to grow and be cultivated) and the lighting period opposite of the display is kept to encourage the macro algae growth. As you are aware, I'm sure, plants feed on CO2 and produce O2... this would encourage more O2 during the night hours and stablize PH.