The present invention generally provides a closed feedback system for operating peripheral devices in response to environmental conditions. Illustrative environmental conditions include well bore pressure, line pressure, fluid levels, flow rates and the like. In one embodiment, a flow controller disposed in a fluid line is operated in response to operating variable readings (e.g., pressure and/or flow rate) taken in the flow line and/or a well bore. The variable measurements are then compared to target values. If necessary, the flow controller is closed or opened to control the rate of fluid flow through the flow line and thereby achieve the desired target values. In another embodiment, the operation of a pump motor is monitored. Operating variables, such as voltage, current and load, are measured and compared to target values. In the event of a difference between the actual values of the variables and the target values, the flow controller is adjusted to affect the head pressure on a pump being driven by the motor. In some cases, the motor operation may be halted or otherwise adjusted.