Settling flux/load in EFDC

Dear EEMS team:

I would like to ask a question about EFDC’s calculation method of settling load. Taking RPOP as an example, is the RPOP settling load of a certain grid on a certain day equal to the RPOP concentration multiplied by settling rate and then multiplied by the grid area? I calculate the nutrient of my model. The source TP load is further higher than the sink TP load, but the nutrient pool in the end is lower than that from the start. So I wonder whether I overlook some sink paths or my calculation method of the settling load is wrong. Please see the attached picture for the detailed process of the strange problems.

I am looking forward to your reply. Thank you so much!