That's basically correct, but just let Your fish tell You. If they head to the top at lights out or by morning--then you probably need more 02. Sometimes adjusting for slightly more surface turbulation will provide all you need without wasting excess C02.You don't use an air pump with a co2 injected planted tank. Atleast not while the lights are on. Some people turn on a air pump at night to make sure they get enough oxygen in the water. I don't and don't have any problems but some do.