The development of reliable criteria for determining the onset of scaling of sparingly soluble salts on reverse osmosis desalination membranes is of great practical significance. Calcium carbonate, which is dealt with in this study, is a commonly encountered membrane scale compound. Reliable modeling and simulation tools of the reverse osmosis operation (accounting for onset and development of scaling) are very important for process optimization, aiming to reduce the effects of scaling and to minimize the use of antiscalants; such comprehensive modeling requires knowledge of key scaling parameters. In recent years a procedure has been developed to extract these parameters by employing a facile testing procedure, involving a small pressurized dead-end filtration cell. Using such a stirred test cell, the conditions are much closer to the actual reverse osmosis desalination process, compared to those in a non-agitated cell. Here, a detailed model of the testing process is developed and a procedure for estimating the scaling parameters is presented, by employing available relevant data. The results of the present work confirm the previous suggestion that fluid agitation in the test cell leads to an improved scaling parameter estimation procedure.