Flow cytometer arrangement comprising ▪ a flow measurement cell, ▪ a mixer, ▪ an incubator (220, 240), ▪ a first pump, a second pump, a third pump and a fourth pump, ▪ an inlet connection, ▪ a dye reservoir (410, 420), and ▪ a sheath fluid reservoir, ▪ wherein the first pump is connected on the inlet side to the inlet connection for suction of sample fluid, ▪ wherein the second pump is connected on the inlet side to the dye reservoir (410, 420) for suction of dye, ▪ wherein the first pump and the second pump are connected on the outlet side to the mixer, in order to pump sample fluid and dye into the mixer, and the mixer is designed to mix the sample fluid and the dye to give a mixture, ▪ wherein the fourth pump is connected on the inlet side to the sheath fluid reservoir for suction of sheath fluid, ▪ wherein the third pump is connected on the outlet side to the flow measurement cell in order to produce a sample jet through the flow measurement cell from the mixture, ▪ wherein the fourth pump is connected on the outlet side to the flow measurement cell in order to produce a sheath jet through the flow measurement cell that ensheaths the sample jet from the sheath fluid, ▪ wherein the mixer (210, 230) is connected on the outlet side to the incubator (220, 240) which is connected on the outlet side to the third pump, characterized in that ▪ the flow cytometer arrangement comprises a control device configured to control the pumps (310, 320, 330, 340), and ▪ the control device is configured to control the first pump and/or the second pump and the third pump in such a way that the third pump sucks in mixture from the incubator (220, 240), and synchronous operation of the first pump and/or the second pump keeps an operating pressure in the incubator (220, 240) at a specified pressure. ▪ a flow measurement cell, ▪ a mixer, ▪ an incubator (220, 240), ▪ a first pump, a second pump, a third pump and a fourth pump, ▪ an inlet connection, ▪ a dye reservoir (410, 420), and ▪ a sheath fluid reservoir, ▪ wherein the first pump is connected on the inlet side to the inlet connection for suction of sample fluid, ▪ wherein the second pump is connected on the inlet side to the dye reservoir (410, 420) for suction of dye, ▪ wherein the first pump and the second pump are connected on the outlet side to the mixer, in order to pump sample fluid and dye into the mixer, and the mixer is designed to mix the sample fluid and the dye to give a mixture, ▪ wherein the fourth pump is connected on the inlet side to the sheath fluid reservoir for suction of sheath fluid, ▪ wherein the third pump is connected on the outlet side to the flow measurement cell in order to produce a sample jet through the flow measurement cell from the mixture, ▪ wherein the fourth pump is connected on the outlet side to the flow measurement cell in order to produce a sheath jet through the flow measurement cell that ensheaths the sample jet from the sheath fluid, ▪ wherein the mixer (210, 230) is connected on the outlet side to the incubator (220, 240) which is connected on the outlet side to the third pump, ▪ the flow cytometer arrangement comprises a control device configured to control the pumps (310, 320, 330, 340), and ▪ the control device is configured to control the first pump and/or the second pump and the third pump in such a way that the third pump sucks in mixture from the incubator (220, 240), and synchronous operation of the first pump and/or the second pump keeps an operating pressure in the incubator (220, 240) at a specified pressure.