In this paper we study mass transport in SiC powder charge, employed as a source of reactive species in SiC bulk crystal growth, coupled with the species transport in the clearance between the powder and the seed. The study is aimed at finding correlation between growth conditions and powder evolution during a long-term growth process. We also examine how the growth conditions and the powder properties (porosity and mean size of SiC granule) influence SIC growth rate at the seed. The theoretical results are compared with available experimental data.