We've had an intermittent issue with this for years. The application is sensing a level, or more accurately the absence of level in smallish ~5-10 liter Pyrex buffer tanks. The OEM solution i.e. a capacitive prox switch for the tank fill signal works very well, except for when the product is high conductivity, such as a 7% NaCl or 24% sugar solution. We don't know if the switch picks up whatever liquid is still adhering to the interior surface of the pyrex, or what. We've tried different sensing distances, but that doesn't seem to matter. The operators end up constantly fiddling with the sensitivity adjustment on the prox switch, and that just doesn't cut it. Any ideas, experience or, suggestions are appreciated.