An increase of the mixing power was obsd. during emptying tanks with turbine-blade impellers of various blade pitch angles. The decrease of blade pitch angle from 60 degrees down to 15 degrees (occurred primarily for the case when the impeller pumped the liq. to the bottom of the tank) resulted in a relative increase in power consumption. For impellers with blades located perpendicular to the agitating plane, this phenomenon did not occur.