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HM Digital Small Handheld TDS Meter with Aquarium Packaging

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  In Stock
  •   Model # TDS-4TMA
  •   UPC 891144000199
  •   Brand HM Digital
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A TDS tester that's ideal for all water purification applications, wastewater regulation, aquaculture, hydroponics, and colloidal silver. Perfect for both consumer or commercial use. Carry one in your pocket at all times!

TDS-4TM is the smallest handheld TDS meter in the world according to HM Digital who holds the original patent for this meter. Beware of imitators, none offer the superior performance of the original TDS-4TM.

TDS-4 Meters measure the amount of Total Dissolved Solids (TDS) within a given sample of water. The measurement is shown in Parts Per Million (PPM).

TDS is the contaminant category removed by the Reverse Osmosis (RO)Membrane itself. The meter can be used to measurse the effectiveness of the membrane only and not the filters used in conjunction with it.

To perform a test on a membrane (2) samples must be drawn. The first is untreated water and the other is RO treated water. Use the TDS reading to calculate a removal ratio. Most Thin Film Composite (TFC) Membranes are effective for 95-98% removal of TDS.


  • The smallest and lightest TDS meter on the market.
  • Sleek design is perfect for personal or consumer use.
  • Advanced microprocessor technology.
  • Hold Function: saves measurements for convenient reading and recording.
  • Auto-off function: the meter shuts off automatically after 10 minutes of non-use to conserve batteries.
  • Measurement Range: 0-9990 ppm. From 0-999 ppm, the resolution is in increments of 1 ppm. From 1000 to 9990 ppm, the resolution is in increments of 10 ppm, indicated by a blinking 'x10' image.
  • Display: large and easy-to-read LCD screen.
  • Factory Calibrated: our meters are calibrated with a 342 ppm NaCl solution. Meters can be recalibrated with a mini-screwdriver.


  • Range: 0 - 9990 ppm (mg/L)
  • Resolution: 1 ppm
  • Accuracy: ±2%
  • ATC: Built-in sensor for Automatic Temperature Compensation of 1 to 50 degrees Celsius (33 to 122 degrees Farenheit)
  • Power source: 2 x 1.5V button cell batteries (included)
  • Battery life: 1000 hours of usage
  • Dimensions: 14 x 2.3 x 1.5 cm (5.5 x .9 x .55 inches)
  • Weight: 34g (1.2 oz)