As acceptance of streaming current monitors (SCM) has grown, so have the technological advances for precise coagulant feed control. Latest developments include a sensor with field replaceable probe cartridges; this development allows SCM use in wastewater and other harsh applications. Another development is improvements to the transmitter module; the new unit outputs a 4-20mA signal and can be interfaced with a variety of input devices such as computers, controllers, or recorders. The third development in control technology is PC-based software to provide comparative analysis of treatment process variables.