Intermittent suction is performed in virtually all MBR employing immersed membranes to improve net permeate flow. It consists of repeated cycles of suction and relaxation. During relaxation time, some of the membrane foulants formed during suction time can be removed by air scouring. Although some productivity loss is inevitable during the pause time, net permeate volume improves in vast majority of the situations. There are no predominant rules in cycle time, but the relaxation time (or pause time) typically takes 10-20% of the total cycle time depending on membrane fouling propensities in the specific location, e.g. any combination of 8-11 minutes on and 1-2 minutes off. Most full scale plants have a capability of modifying the cycle time depending on the membrane fouling rate and wastewater flow rate.