An ink supply unit for supplying ink to a printhead includes an elongate manifold defining a recess for receiving the printhead, and a plurality of ink slots in fluid communication with a back surface of the printhead, the plurality of ink slots being grouped into sets; and an ink supply comprising an elongate housing and a partition unit that together define a plurality of elongate ink chambers, each elongate ink chamber being in fluid communication with a respective set of ink slots. The ink supply further comprises a baffle unit including a number of spaced apart baffles extending into each ink chamber, the baffle unit for reducing acceleration of ink in a longitudinal direction along a length of the elongate housing.