The sensor measures the complex impedance between two metal rods that are inserted into the soil or substrate. The data are sent to a web server where the water content and EC are calculated. In one of the two metal rods, a temperature sensor is embedded, the temperature is also sent to the web server. On the website www.aquatag.net the data can be monitored in graphs, and as a ‘heat-map’. The sensor works on 3 AA batteries that need to be replaced or charged annually. There are different versions of the sensors for different applications: a long one for open soil, a short one for pots, and one with needles for seedlings in trays.