[How to Calibrate]With 4.01/6.86/9.18 ph buffer powder and ORP buffer powder (Not all three packs of calibration powder need to be calibrated, according to the actual situation, one powder bag can also be calibrated). Prepare three cups of 250ML water and pour in the buffer powder. Step 1: Turn on the power supply of the ph meter. : Press the MODE and CAL button. Press the MODE and CAL button for about 6 seconds, and the ph meter flashes three to complete the calibration. [8-in-1 pH Meter]ph meter has a 8-in-1 function, which can measure PH, TDS, Temp, EC, Salinity,ORP,S.G,H2 with high precision at the same time. All-round measurement of water quality to healthy water quality. The detailed manual included will show you how to get the best accurate and stable reading. [High Accuracy Digital pH Meter]PH measurement 0-14, TDS 0-200000ppm,EC 0-200000/cm,Salinity 0-20%,ORP 1999MV,H2 0-2400PPb,S..000-1.222,temperature 0-60. Backlit LCD Design guarantees that you can read the measuring results in any condition. One-button lock reading function helps lock reading. [The Importance of Water Quality] The water is too acidic or too alkaline, which has adverse effects on human body. TDS water quality detection pen can help us to detect the composition of drinking water at any time. Water quality is closely related to health, and good water quality can delay aging. 8-in-1 PH water quality testing pen is a household necessity. [Widely Used] pH/TDS meter Perfect or laboratory uses. Water ph tester can be used to test drinking water, swimming pools, pH balance in aquarium, bath tub, spa, wine, beer and any other liquids, pH pen make you get the quality of water at any time and get accurate data. Material: Plastic colour: As shown Package Contents: 1 x 8-in-1 pH Tester Only the above package content, other products are not included. Note: Light reflection and different displays may cause the color of the item in the picture a little different from the real thing. The measurement allowed error is +/- 1-3cm.