We propose a new approach to optimization of SiC bulk crystal growth based on modeling. The idea is to employ a special software tool "virtual reactor" (VR) operated by the user of the code as an actual crystal growth system. The software tool includes the models necessary to simulate global heat transfer in the whole growth system and inside the crucible including radiative transport through the semi-transparent SiC crystal. It is known that accurate material properties are crucial for thermal modeling of SIC growth. A database with material properties of SIC crystal and powder, graphites and insulation is included into the VR-software. an advanced model of species transport during sublimation growth of SiC crystals is developed. The model includes convective and diffusive species transport, surface kinetics based on the Hertz-Knudsen equations and chemical models for all solid surfaces (SiC crystal, SiC source, graphite wall). A model to predict type of parasitic deposit and the corresponding deposition rate is combined with the mass transport model available in the VR-software. In this paper, we show the results of simulation of a large-size SIC bulk crystal growth using the VR-software tool with the focus on poly-SiC deposit formation on the graphite crucible lid around the crystal.