With the CTD versions (Conductivity, Temperature, Depth) of the 'DCX' level data loggers for depths of up to 200 m, Keller offers a highly integrated complete solution for water management. The data logger for long-term monitoring stores over 50,000 measured water level values with a time stamp as well as the corresponding measured values for conductivity and temperature. With a diameter of 22 mm, the combination probes are suitable for all monitoring wells from 1 inch nominal diameter. Depending on the application, the DCX-22 CTD series level probes with integrated data logger are available in a stainless steel housing or in other materials. The maintenance-free, battery-operated level probes with data logger are optionally available with a GSM module for remote monitoring. All products in the DCX-22 series are available as CTD level probes with integrated conductivity and temperature sensors. The level probes have been supplemented with high-precision conductivity sensors. Four outer platinum electrodes are used to feed in a defined alternating current, while two inner electrodes are used to measure a voltage as a measure of the conductivity of the medium. The four measuring ranges 0 to 200 μS/cm, 0 to 2 mS/cm, 0 to 20 mS/cm and 0 to 200 mS/cm with a measuring accuracy of ±1 % are available for measuring conductivity.