Abstract: A chemical feeder system includes an aqueous chemical contained in a chemical source, the chemical source connected with a fluid stock through a chemical flow conduit and a feeder assembly connected within the chemical flow conduit that includes a metering device, a flow rate sensor and a controller operationally connected between the flow rate sensor and the metering device. A method of controlling the flow rate a treating chemical is applied to a fluid stock includes the steps of positioning a flow sensor upstream of a chemical metering device in a chemical flow conduit between a chemical source and fluid stock, flowing a treating chemical from the source through the chemical flow conduit, determining a desired application flow rate of the treating chemical and adjusting the metering device in response to a flow rate reading at the flow rate sensor to achieve the desired application flow rate.