An acute renal replacement therapy apparatus, comprising at least two feedback control means (110, 120), each including: an estimated volume calculation means (112, 122) adapted to calculate an estimated volume based on a set flow; a comparing means (114, 124) adapted to compare the estimated volume with a measured volume; a volume deviation determining means adapted to determine a volume deviation based on the result of the comparison; a correction calculation means (116, 126) adapted to calculate a correction amount based on the determined volume deviation; a flow control generation means (118, 128) adapted to generate a controlled flow control signal based on the calculated correction amount and the set flow; and a feedback control output means adapted to output the controlled flow control signal to a pump (134, 144) individually associated with each feedback control means and forwarding fluid from a fluid source and/or pulling fluid into a fluid sink, a flow correction distribution means characterized by an input means adapted to input correction required signals calculated by and output from the correction calculation means in each of the at least two feedback control means; a stability detector logic means adapted to input at least two flow stability indication signals and to output a correction stability signal; a switching means adapted to input the correction stability signal from said stability detector logic means and to switch, depending on the state of the correction stability signal, between a first state yielding a first net fluid removal rate correction limit for a stable condition and a second state yielding a second net fluid removal rate correction limit for an unstable condition; a limited correction signal calculation means adapted to calculate a limited correction signal for each of the input correction required signals based on the first or second state net fluid removal rate correction limit; and an output means adapted to output each calculated limited correction signal to the feedback control means from which its underlying correction required signal has been received. an estimated volume calculation means (112, 122) adapted to calculate an estimated volume based on a set flow; a comparing means (114, 124) adapted to compare the estimated volume with a measured volume; a volume deviation determining means adapted to determine a volume deviation based on the result of the comparison; a correction calculation means (116, 126) adapted to calculate a correction amount based on the determined volume deviation; a flow control generation means (118, 128) adapted to generate a controlled flow control signal based on the calculated correction amount and the set flow; and a feedback control output means adapted to output the controlled flow control signal to a pump (134, 144) individually associated with each feedback control means and forwarding fluid from a fluid source and/or pulling fluid into a fluid sink, a flow correction distribution means characterized by an input means adapted to input correction required signals calculated by and output from the correction calculation means in each of the at least two feedback control means; a stability detector logic means adapted to input at least two flow stability indication signals and to output a correction stability signal; a switching means adapted to input the correction stability signal from said stability detector logic means and to switch, depending on the state of the correction stability signal, between a first state yielding a first net fluid removal rate correction limit for a stable condition and a second state yielding a second net fluid removal rate correction limit for an unstable condition; a limited correction signal calculation means adapted to calculate a limited correction signal for each of the input correction required signals based on the first or second state net fluid removal rate correction limit; and an output means adapted to output each calculated limited correction signal to the feedback control means from which its underlying correction required signal has been received.