How can I activate COD parameter in the water column

Hello! I want to know the concentration of COD in the water column. But when i view the result of the model, it shows that the concentration of COD in the water column is not simulated. So, what should i do to make the model to simulate the COD in the water column?

Have you turned COD on? It is enabled in the WQ kinetics as shown in Fig. 2 here:

https://eemodelingsystem.atlassian.net/wiki/spaces/EK/pages/1034354693/Kinetics