The MPC controller of campo and morari ,(1989),was formulated so that these is no offset after the prediction horizon. This is the tuning parameter in this case, and it can be shown that for any given disturbance, there is a critical prediction horizon, i.e. the time at which the tank would overflow, with no controller action. As the prediction horizon is increased, the MRCO objective is continually improved until this critical horizon is reached. Thereafter, the settling time is only increased, with no further benefit to flow filtering.