เครื่องวัดกรดด่าง EC900: Waterproof DO Kit 9-in-1 Meter DO/pH/EC/TDS เครื่องวัดกรดด่าง 9-in-1 Meter with Lab-Quality Performance Features: Measures Dissolved Oxygen concentration/saturation, pH, mV, Conductivity, TDS, Salinity, Resistivity and Temperature Automatic salinity compensation and manual barometric pressure compensation for DO measurements One button pH calibration (4, 7, and 10pH) Choice of 3 point pH calibration for better accuracy One point Conductivity calibration - automatically recognizes 8 calibration solutions from USA, Europe and China series Automatic Temperature Compensation (non-linear compensation for purified water <10µS/cm to improve measuring accuracy)