A pool cleaning robot, that may include a filter; a first impeller; a driving unit arranged to move the pool cleaning robot; an external housing that comprises a first inlet and a first outlet; a first pump motor arranged to rotate the first impeller; wherein when the first pump motor rotates the first impeller rotates along a first rotational direction causes fluid to be drawn through the first inlet and causes a first portion of the fluid to be filtered by the filter to provide filtered fluid that exits through the first outlet of the housing; wherein when the first pump motor rotates the first impeller rotates along a second rotational direction that is opposite to the first rotational direction, thereby performing a backwash operation of the filter.