A master controller identifies a flow ratio setpoint for at least one of a process gas or a carrier gas flow to a process chamber through a set of mass flow controllers. The master controller determines a flow setpoint for the at least one of the process gas or the carrier gas through the set of mass flow controllers based on the identified flow ratio setpoint. The master controller controls the at least one of the process gas flow or the carrier gas flow through each of the set of mass flow controllers according to the determined flow setpoint for each of the set of mass flow controllers and based on a back pressure reading provided by a back pressure sensor.