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Triple Inline TDS Meter TRM-1 - HM Digital

Triple Inline TDS Meter TRM-1 - HM Digital


Item #: HB00024

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The TRM-1 is a three-sensor TDS monitor that can monitor the TDS levels at three different points. It is perfect for RO/DI systems and other types of filtration and purification systems.

  • Displays TDS levels of the three sensing points with electrode probes.
  • Highly efficient and accurate due to its advanced microprocessor technology.
  • Auto-Off function conserves battery power. The unit shuts off automatically after 10 minutes of non-use.
  • Dual Range 0-9990 ppm (From 0 - 999 ppm the resolution is 1 ppm. From 1000 to 9990 ppm, the resolution is 10 ppm, indicated by a blinking `x10` image.)
  • Factory Calibrated: calibrated with a 342 ppm NaCl solution. Meters can be recalibrated with a mini-screwdriver.
  • Installs quickly and easily.
  • Range: 0-9990 ppm
  • Accuracy: ±2%
  • Conversion Factor: NaCl (avg. 0.5)
  • Fittings: 1/4" standard**
  • Cable Length: 24.5" (including sensor)
  • Power source: 2 x 1.5V button cell batteries (LR44 or equivalent; included)
  • Battery life: approx. 1000 hours of continuous use
  • Size: 7.6 x 2 x 4.7 cm (3 x .8 x 1.9 in.)
  • Weight: 79.4 g (2.8 oz.)
**T-fittings not included

Manufacturer information

HM Digital, Inc.
Established in 1987, HM Digital, Inc. (formerly known as Heemang Electronics) is an original equipment manufacturer (OEM) that has been recognized worldwide for providing the best values in water testing instrumentation, especially the increasingly popular TDS meter.

5 Stars


Reviewed on
February 22, 2018

Yes, I would recommend this.

No Guess Work, will save money on filters, resin and carbon

Pros: Makes reef life easier

Cons: None that I can see

I recently upgraded my RO/DI to 6 stage and added this in hopes of identifying when elements of the unit are spent and need changes. It perfectly co-witnesses with my handheld HM TDS-3 meter. As an aside I also installed the Smsrt Buddie booster pump, cut my water making time in half. Will definitely be able to identify a bad membrane, carbon or resin.

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Reviewed on
August 09, 2017

Yes, I would recommend this.

Now you know

I never really knew when to change the resin or cartridges and now I know from the levels on the tds. Great warranty from manufacture as well.

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Reviewed on
November 06, 2016

Yes, I would recommend this.

Must have for your RO/DI

I have a hand held meter and this is spot on with the hand held meter. I love that I can get an overall idea of how my RO/DI is performing with this meter. I replaced my dual meter with this one as I was only measuring input pre filters and output after the DI. This unit allows you get a pre filter reading, post RO and post DI. Those reading allow me to better monitor when filters and membranes need changing. Yes is does not compensate for temp but its a great tool to get an idea of how your system is performing. I strongly recommend this product.

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jay banks

Reviewed on
November 12, 2014

Yes, I would recommend this.

Excellent service

What more needs to be said - EXCELLENT SERVICE!

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