The present invention is an apparatus and method for introducing a dry material into a fluid stream in a way that ensures a predictable, highly accurate and consistent application of the material where the fluid stream may be fixed or variable, where the material is handled and metered in dry bulk form and may be highly soluble or nearly insoluble, and in a manner that continuously and automatically adjusts the application rate to compensate for varying material bulk density, as well as, and in addition to, varying fluid flow rates or chemical composition, in order to provide a precise fluid treatment level at all times. The present invention incorporates the necessary means to store large quantities of the dry process amendment as an integrated and dust-free function of the apparatus and process, and is capable of monitoring and adjusting material levels and introduction rates in real time in response to variations in density, fluid flow rate and/or chemistry composition.