A system for managing fluid for accurate continuous venovenous hemofiltration, comprising: (a) a hemofilter configured to continuously filter unfiltered blood to extract ultrafiltrate, thereby configured to produce filtered blood; (b) a first container filled with replacement fluid, wherein the replacement fluid is configured to be transferred from the container to the filtered blood; (c) a second container and the first container coupled to a translating arm, wherein the translating arm is configured to move to simultaneously allow the replacement fluid to be transferred from the first container to the filtered blood and allow the ultrafiltrate to be transferred from the hemofilter to the second container, the amount of the replacement fluid and the ultrafiltrate transferred being equal to each other; characterized by: (d) at least one sensor being structurally connected to the translating arm to continuously monitor the relative position of the translating arm, thereby configured to determine whether there is replacement fluid contained in the first container and ultrafiltrate contained in the second container; and (e) means configured to cause the translating arm to stop and reverse its direction upon the at least one sensor detecting that the translating arm is in a minimum or a maximum position in connection with the first container and the second container, wherein, in a first phase, the first container is configured to be refilled with additional replacement fluid at the same time as the ultrafiltrate is configured to be emptied from the second container, and wherein, in a second phase, the replacement fluid is configured to be transferred from the first container at the same time as the ultrafiltrate is configured to be extracted from the hemofilter and configured to be transferred to the second container. (a) a hemofilter configured to continuously filter unfiltered blood to extract ultrafiltrate, thereby configured to produce filtered blood; (b) a first container filled with replacement fluid, wherein the replacement fluid is configured to be transferred from the container to the filtered blood; (c) a second container and the first container coupled to a translating arm, wherein the translating arm is configured to move to simultaneously allow the replacement fluid to be transferred from the first container to the filtered blood and allow the ultrafiltrate to be transferred from the hemofilter to the second container, the amount of the replacement fluid and the ultrafiltrate transferred being equal to each other; characterized by: (d) at least one sensor being structurally connected to the translating arm to continuously monitor the relative position of the translating arm, thereby configured to determine whether there is replacement fluid contained in the first container and ultrafiltrate contained in the second container; and (e) means configured to cause the translating arm to stop and reverse its direction upon the at least one sensor detecting that the translating arm is in a minimum or a maximum position in connection with the first container and the second container, wherein, in a first phase, the first container is configured to be refilled with additional replacement fluid at the same time as the ultrafiltrate is configured to be emptied from the second container, and wherein, in a second phase, the replacement fluid is configured to be transferred from the first container at the same time as the ultrafiltrate is configured to be extracted from the hemofilter and configured to be transferred to the second container.