An system for dispensing liquid and solid materials comprises a tank (14); one or more liquid feeders (12) configured to dispense one or more liquids into the tank; a powder hopper (22) comprising a powder inlet, a powder outlet, and a valve (28) configured to open and close the powder outlet, the powder outlet being coupled to the tank (14); one or more powder feeders (26) coupled to the powder inlet of the powder hopper; a first scale (24) configured to measure the mass of powder dispensed into the powder hopper; a second scale (16) configured to measure the mass of the liquids dispensed into the tank; and a control system (18) configured to control the dispensing of liquids and powders based at least in part on the mass measurements from the first and second scales.