I've read posts by several members who set an air pump on a timer to come on after the CO2 goes out to provide oxygen without offgassing precious carbon. The other thing to consider is surface agitation does not necessarily have to mean current in the tank. Example, a HOB dropping water into the tank or small powerhead pointed at the surface will mix things up plenty without providing much actual current in the tank. As an example, I use a powerhead in my 20H shrimp tank but it's pointed 45 degrees up toward the surface. I get good water flow and plenty of surface agitation, but unless the shrimp swim right into the outflow they aren't blown around the tank at all.
During the day the plants should provide plenty of oxygen. If you're concerned about things at night, an air pump on a timer is a solid plan if you can't get enough surface agitation out of your filtration method.
During the day the plants should provide plenty of oxygen. If you're concerned about things at night, an air pump on a timer is a solid plan if you can't get enough surface agitation out of your filtration method.
