A continuous ink jet printer comprising an ink tank, an ink pump and at least one suction device (35, 49), the ink tank, the ink pump and the at least one suction device (35, 49) being provided in an ink circuit in which the ink pump is configured to pump ink from the ink tank through the ink pump, to an inlet of the at least one suction device (35, 49), through the at least one suction device (35, 49) and then back to the ink tank, the at least one suction device (35, 49) further comprising at least one suction inlet, the at least one suction device being arranged to create suction from the flow of ink through it; the printer further comprising: an ink feed line connected to the outlet side of the ink pump configured to receive pressurised ink therefrom and supply it to an ink gun of a print head; a gutter line connected to a suction inlet of the at least one suction device (35, 49) configured to allow ink to be sucked away from a gutter of the print head; an ink top-up line connected to a suction inlet of the at least one suction device (35, 49) configured to allow ink to be sucked into the ink circuit, and a solvent (diluent) top-up line connected to a suction inlet of the at least one suction device (35, 49) configured to allow solvent (diluent) to be sucked into the ink circuit, wherein the printer further comprises a first fitting for connecting an ink container to the ink circuit at the ink tank or at a location in the ink circuit that is (a) between an outlet of the at least one suction device (35, 49) and an inlet of the ink tank or (b) between an outlet of the ink tank and an inlet of the ink pump or (c) between an outlet of the ink pump and an inlet of the at least one suction device (35, 49). the at least one suction device (35, 49) further comprising at least one suction inlet, the at least one suction device being arranged to create suction from the flow of ink through it; the printer further comprising: an ink feed line connected to the outlet side of the ink pump configured to receive pressurised ink therefrom and supply it to an ink gun of a print head; a gutter line connected to a suction inlet of the at least one suction device (35, 49) configured to allow ink to be sucked away from a gutter of the print head; an ink top-up line connected to a suction inlet of the at least one suction device (35, 49) configured to allow ink to be sucked into the ink circuit, and a solvent (diluent) top-up line connected to a suction inlet of the at least one suction device (35, 49) configured to allow solvent (diluent) to be sucked into the ink circuit, wherein the printer further comprises a first fitting for connecting an ink container to the ink circuit at the ink tank or at a location in the ink circuit that is (a) between an outlet of the at least one suction device (35, 49) and an inlet of the ink tank or (b) between an outlet of the ink tank and an inlet of the ink pump or (c) between an outlet of the ink pump and an inlet of the at least one suction device (35, 49). an ink feed line connected to the outlet side of the ink pump configured to receive pressurised ink therefrom and supply it to an ink gun of a print head; a gutter line connected to a suction inlet of the at least one suction device (35, 49) configured to allow ink to be sucked away from a gutter of the print head; an ink top-up line connected to a suction inlet of the at least one suction device (35, 49) configured to allow ink to be sucked into the ink circuit, and a solvent (diluent) top-up line connected to a suction inlet of the at least one suction device (35, 49) configured to allow solvent (diluent) to be sucked into the ink circuit, wherein the printer further comprises a first fitting for connecting an ink container to the ink circuit at the ink tank or at a location in the ink circuit that is (a) between an outlet of the at least one suction device (35, 49) and an inlet of the ink tank or (b) between an outlet of the ink tank and an inlet of the ink pump or (c) between an outlet of the ink pump and an inlet of the at least one suction device (35, 49).