air? like an air pump/stone? benefits are more surface agitation, and thats about it. it does little to actually oxygenate the water, BUT the agitation it creates is good (however a simple waterfall on your HOB filter already does a good job). if you go with plants, air is decent, but be warned that it off gasses CO2 in the water so your plants may not grow fast. but it shouldn't kill them. IMO keep the air until you get lots of plants you like in there, then stop the air pump usage, let the plants produce air (plus your filter agitating the water, but with lots of plants it should make a water fall since4 that does the same off gassing effect). Once the plants are there, put the tank on a regular light schedule on a timer and the oxygen production during the day time would be good. you could run the airstone during night if youre really worried, but i haven not seen any issues.