The SCA Ortviken mill in Mid Sweden has capacity to produce 2150 adtpd of TMP at CSF=150 ml in 60" double disc refiners in a single stage operation. The objective of this paper is to present models for CSF and long fibre content control in the refining process and to show the results with and without the control system. The control system is model-based. Results showed better CSF control with the application. The variability reduction was 50%.