Problem about carbon dioxide in WQ modules

Hello everyone, I had been using EFDC WQ module to simulate heterotrophic respiration and denitrification processes in a river channel, and I had successfully reproduced the temporal variations of several water quality parameters such as DO, POC, and NH₃.

From my understanding, both heterotrophic respiration and denitrification should produce inorganic carbon, which in the model should correspond to CO₂. Therefore, I enabled the CO₂ option in WQ modules and reran the model. However, I was not able to generate any simulation results for CO₂.

Does anyone know what might be causing this problem? I don’t give CO2 External forcing data,is it necessary to assign time series data to model boundaries ? Or is it possible that the simulation of inorganic carbon (CO₂) in EFDC is not fully implemented or coupled with the biogeochemical processes?

My version is EEMS 10.3.Below are some of my setting.