Item type: Fish Tank TDS Tester Material: ABS Measurement range: 0-9990ppm Accuracy rating: ±2% Battery: 2 x 1.5V small cell battery Size: Approx. 155x31x23mm/6.1x1.2x0.9in TDS Meaning: TDS (Total Dissolved Solids) is the total amount of solid matter dissolved in water, expressed as 1/1000 g (mg/L) or 1/1000000 (ppm). It shows how many milligrams of dissolved solids are dissolved in 1 liter of water. A higher tds value indicates more impurities in the water. Water quality test steps: 1. Take off the pen holder and turn on the on switch; 2. Put the pen into the solution to be tested, the height of the solution should not exceed 5cm (starting from the pen end); 3. Gently stir the test pen in the solution to be tested to ensure that there is no air and bubbles around the probe during the test, and it is fully in contact with the aqueous solution. After the value is stable, the value can be read on the screen. For reading convenience, press the HOLD button to lock the value. 4. After use, please wipe the tip of the pen and cover the pen cover. Temperature test operation: 1. Press the TEMP button to display the display temperature display; 2. Take off the pen holder to measure the temperature in the solution or air; 3. Continue to press the TEMP button to return to the water quality test. The temperature is ambient temperature, divided into Celsius and Fahrenheit.