This paper deals with effect of impeller type on off-bottom particle suspension. On the basis of numerous suspension measurements correlations are proposed for calculation just suspended impeller speed for eleven impeller types and geometries in the wide range of concentrations and particle diameters. The suspension efficiency of tested impellers has been compared by means of the power consumption required for off-bottom suspension of solid particles. (C) 2010 The Institution of Chemical Engineers. Published by Elsevier B.V. All rights reserved.