A biofiltration system is currently being tested as an alternative to maintain indoor air quality within an office building setting. The system is based on a complex plant community with both terrestrial and aquatic components. CO2 dynamics within the space offer a means of evaluating its potential efficacy. A model is presented based upon both exponential and linear processes, which accurately describes diurnal changes in CO2 levels and the removal of introduced CO2. The exponential dynamics indicate increasing rates of sequestering with increasing exposure levels. The CO2 is eventually fixed through the process of photosynthesis, but is most likely initially sequestered in the aquatic component of the system. The removal of the contaminant from the atmosphere and into the aquatic phase where it is subsequently metabolized by the biomass suggest the system may be an effective filter for removing contaminants from indoor settings.