Ez adjust impeller clearance

A pump features a bearing sleeve couples to a pump shaft, and includes a bearing sleeve surface having bores for receiving fasteners; and an adjusting nut having a central bore with central bore threads to rotationally couple to pump shaft threads, is configured to rotate in relation to the bearing sleeve and move the pump shaft axially to adjust an impeller clearance between a working side of an impeller arranged on the pump shaft and a casing of the pump, and is configured with an adjusting nut surface having openings different in number than the bores, sets of corresponding bores and openings aligning at angular adjustment intervals, e.g. every 9 or 15°, when the adjusting nut is rotated in relation to the bearing sleeve in either direction in order to receive fasteners to couple the adjusting nut to the bearing sleeve when the adjustment of the impeller clearance is completed.