The Mini Doser EC nutrient controller can work in units of EC, CF or TDS. The complete kit comes with a sensor and two economy solenoid valves pre-wired on a small panel. The controller continuously measures the nutrient concentration in the mixing tank and adds A and B nutrients as required to maintain the EC set point. The controller counts the number of doses and in the event of the dose count per hour exceeding a set value an alarm can be sounded. In addition, alarms can be set to sound should the EC wander outside user set limits. If the dose count per hour exceeds a user setting - the controller will stop dosing. The solenoid valves supplied are resistant to acids and alkalis at a concentration of 2% which is adequate for most nutrients. Specially chemically resistant valves or peristaltic pumps are also avaialble. This is a great little machine that is aimed at the budget conscious and those who do not need a computer interface.