In any planted aquarium Carbon dioxide (CO2) is essential for better growth of plants. CO2 in the water comes from fish respiration, or is dissolved from the atmosphere. But in a dedicated planted aquarium you need more CO2 from outside for better growth of aquatic plants. So you need to do the same so that the plants get enough CO2. The amount of dissolved CO2 is not proportional to the amount of dissolved 02. These two factors are independent of each other. Proper aeration and circulation of water will ensure that requirements for both gases are met.

The growth rates of aquatic plants are related with availability of carbon and the plant