Check the listing for details. Digital TDS/pH testing Meter Pen Type pH Meter for Hydroponics,Household Water. Condition: New. Listed at 4.81 USD. Membrane Solutions pH Meter/TDS Meter ,Digital Water Quality Tester,0~9990 PPM, EC and Temperature Measurement; 0.01 PH High Accuracy with 0-14 PH Measurement Range Digital PH Meter Water Tester This pH meter is affordable and useful for those who need a PH tester for household and laboratory use. It's not only ideal for household or laboratory use. Also suitable for testing pH balance of drinking water, pool, aquarium, food Project, RO system, Spa, or hydroponics. Water Hardness Digital Tester Digital TDS Meter simply provides reliable and quick measurements for most regular water solutions' purity testing, such as drinking water, pool, aquarium, RO system, Spa, or hydroponics; Appropriate for wide range of applications. Calibration steps: The PH Meter Calibration steps: (1) Prepare 3 cups of pH: 4, 6.86, 9.18 calibration solution. (2) Put the pH meter into the first cup of calibration powder solution with a pH of 6.86, and press "CAL" to calibrate it to 6.86. Finally, rinse the PH electrode area with distilled water. (3) Put the pH meter into the cup of calibration powder solution with pH 4, and press "CAL" to calibrate it to 4.08. Rinse the PH electrode area with distilled water. (4) Put the pH meter into the cup of calibration powder solution with a pH of 9.18, and press "CAL" to calibrate it to 9.18. Finally, rinse the PH electrode area with distilled water. It will be calibrated successfully! The TDS Meter Calibration step: (1) Prepare a cup of 500 ppm water. (2)Press the "ON" button and insert the pen into the adjusted water. (3)Long press "shift" 5s to release, and then press "hold" key. (4)The TDS Meter will be calibrated to 500ppm. Package list1: 1X PH meter3X calibration powder1X box1X instruction manual Package list2: 1* EC&TDS Meter1* Storage Box Package list3: 5X PH meter15X calibration powder5X box5X instruction manual Package list4: 10X PH meter30X calibration powder10X box10X instruction manual Package list5: 5* EC&TDS Meter5* Storage Box Package list6: 10* EC&TDS Meter10* Storage Box Q&A Q: How to calibrate a pH meter? A: ph Meter had been calibrated by manufacturer in advance Q:does the TDS table need to be calibrated? A:no, it doesn't, the tds meter is calibrated automatically. Q:can it power off automatically? A:yes, and this function can save batteries Q:What do I need to pay attention to when using the instrument? A:Instrument is non waterpfoof, do not throw the instrument into the solution or make the solution over the immersion line, to avoid the circuit board short out.