HI 9813-0 allows you to measure pH, EC (conductivity) and TDS with just one instrument! This meter has a full-spectrum pH measurement range. The EC range goes to 4.00 mS/cm. In the TDS range, both instruments use a conversion factor from 0.56 to 0.72 for fertilizer readings, to ensure your measurements fully conform to industry standards. The specially engineered HI 1285-0 probe is interchangeable and the pH electrode utilizes a fiber junction and gel electrolyte which are particularly suitable when used in fertilizer solutions. HI 9813-0 and HI 9813-5 measure TDS in the 0 to 1999 ppm range. HI 9813-5 also performs temperature measurements, with the special probe HI 1285-5.