Particle removal from gas streams is effectively accomplished by jet-pulsed bag filters that are usually operated between two preset pressure differences across the filter, the upper and the lower level. The optimal choice of these pressure levels is given, when the ratio of the time span of a filter cycle and the number of jet pulses per cleaning step reaches a maximum. Based on experimental data of a pilot plant filter it is found that for a given upper pressure difference the filter has its optimal lower pressure difference at a surprisingly low level. But the optimum is not very pronounced over a wide range of pressure difference.