In the air, the carbon occurs as carbon dioxide (CO2). It is brought into the air by breathing plants and animals and by decaying or burning organic substances. Botany teaches that sugar is built up from CO2 and water. From this, starch, fat, pulp and other substances can arise again. Protein also contains carbon. Thus it becomes understandable that the carbon sometimes makes up 50% of the plant's dry matter. The carbon is therefore a very important element for the structure of the plant. The air has 0.03% carbon dioxide. However, this low content is sufficient.
6H2O + 6CO2 - Light à C6H12O6 + 6O2
Simply put: Water + Carbon - Light à energy
The more CO2 the more energy the plant can make if there is enough water and light. Inside growers that create too much underpressure (large extraction system - small entrance) always get smaller plants due to the thin air (little CO2) than if they ensure better air pressure.