This paper is devoted to the stability analysis of 3D convective flow in the horizontal channel filled by the porous medium. Solute precipitation (solute sorption) by the porous medium is taken into account within the linear MIM approach. The solute concentration difference across the channel and the external filtration flux are assumed as constant. As a result, conditions of the appearance of two-dimensional convection regimes with respect to possible three-dimensional perturbations were obtained, which made it possible to estimate the range of parameters in which the two-dimensional convection regimes can be observed. The dependencies of the parameters of two-dimensional regimes on the parameters of the problem and on the thickness of the channel are discussed.