Like all plants, cannabis needs carbon dioxide to survive. But when plants are in a contained space, the CO2 in the air will quickly be depleted and replaced by oxygen without proper airflow.This means we need to replenish it in some way. Your setup should have 2-way air circulation, so the cool fresh air filled with CO2 goes in, while the used air goes out.
Yes indeed! Adequate airflow is just as important as light!