DescriptionGLUN TDS Meter is a great tool for home and professional use to determine the ppm (parts per million), Ideal for a variety of professional and home uses such as drinking water, hydroponics, aquariums, aquaculture, pool & hot tub, spa, car wash, food & beverage, coffee, laboratory & scientific, colloidal silver, ecology testing, laboratory & scientific, and more!. Trouble shooting steps to use the product: 1)Remove the protective cap.2)Turn the TDS meter on.3)Immerse the meter into the water solution up to the maximum immersion level (2”).4)Waiting until the display stabilizes, The TDS meter automatically compensates for temperature variations. Once the readout is stabilized (30 to 45 seconds and then press the hold button to save readings.5)After usage, shake off water from your meter or wipe it with a tissue