--- product_id: 6991115 title: "Commercial In-Line Dual TDS Monitor" brand: "hm digital" price: "€ 79.12" currency: EUR in_stock: true reviews_count: 13 category: "Hm Digital" url: https://www.desertcart.hr/products/6991115-commercial-in-line-dual-tds-monitor store_origin: HR region: Croatia --- # Real-time in/out water TDS monitoring Long-lasting 13,000-hour battery life Advanced dual-probe microprocessor tech Commercial In-Line Dual TDS Monitor **Brand:** hm digital **Price:** € 79.12 **Availability:** ✅ In Stock ## Summary > 💧 Stay ahead with precision water quality insights—because your system deserves the best! ## Quick Answers - **What is this?** Commercial In-Line Dual TDS Monitor by hm digital - **How much does it cost?** € 79.12 with free shipping - **Is it available?** Yes, in stock and ready to ship - **Where can I buy it?** [www.desertcart.hr](https://www.desertcart.hr/products/6991115-commercial-in-line-dual-tds-monitor) ## Best For - hm digital enthusiasts ## Why This Product - Trusted hm digital brand quality - Free international shipping included - Worldwide delivery with tracking - 15-day hassle-free returns ## Key Features - • **Extended Battery Life:** Up to 13,000 hours of continuous operation with included AA batteries—maintenance-free monitoring. - • **Instant Performance Insights:** Visual LCD display delivers real-time data to optimize filtration and system efficiency. - • **Precision Dual-Probe Monitoring:** Simultaneously track feed & product water quality for unmatched accuracy. - • **Advanced Microprocessor Accuracy:** Leverages cutting-edge tech for reliable, stable TDS readings every time. - • **Plug-and-Play Industrial Integration:** Effortlessly installs on car washes, manufacturing lines, and food processing systems. ## Overview The HM Digital DM-2 Commercial In-Line Dual TDS Monitor features advanced microprocessor technology and dual electrode probes to provide precise, real-time measurements of total dissolved solids in feed and product water. Designed for industrial applications like car washes and food processing, it offers easy installation with quick-lock fittings and boasts a long 13,000-hour battery life, ensuring reliable, continuous water quality monitoring to optimize filtration system performance. ## Description Product Description Commercial In-Line Dual TDS Monitor DM-2 with Advanced Microprocessors. From the Manufacturer Commercial In-Line Dual TDS Monitor DM-2 with Advanced Microprocessors. Review: Reliable, accurate, convenient TDS meter. - I have used a GE Reverse Osmosis (RO) water purification system for nearly 10 years. I have been using a single portable total dissolved solids (TDS) meter to check my water and I have had very little need for this more sophisticated device until things started to go wrong due to the age of the RO system. I started seeing poorer quality water, and thought I needed a set of new filters (RO filter, pre and post filters). It turned out that I needed a new shut-off valve, but on the way to this conclusion I installed one of these DM-2 meters. I now have two of them. Each meter has two probes to measure TDS. I installed two probes on the input and output of the post-filter, and two probes on the input and output of the pre-filter. This arrangement allows the two input probes to measure the TDS before and after the RO filter, and the two output probles to measure the performance of the pre- and post-filters. I have checked the calibration of the DM-2 instrument using a standard sodium chloride solution and it was accurate as shipped to me. The meter and its probes are reliable and stable measurement devices. They use the electrical conductivity of the water to estimate the TDS of the water. My purified water comes out to be in the 3-10 parts per million (ppm) range, and my input is softened well water and comes out to be around 145 ppm. For 5 ppm RO water, this is ((145-5)/145)*100% or 96% RO filter efficiency. This efficiency varies with the type of RO filter in use. When you use this device, its important to understand exactly what you are measuring. It turns out that the output of the RO filter is pretty reliable and stable, but a new post-filter tends to pollute the water with preservatives and other particles that I know nothing about. Hence, measuring TDS at the output of the post-filter might make you think the RO filter is not working. However, as the filter washes through over a couple of days, the TDS will improve. All the while, the TDS from the RO filter itself is usually just fine right from installing the RO filter. These instruments come standard with 1/4" quicklock plastic "T" fittings, which allow the probes to penetrate right into the middle of the water stream. Some of my water lines are 3/8" so I used 3/8" "T" fittings which I purchased separately. As these fittings are a bit bigger than the 1/4" fittings only the probe tips stick into the water stream. This caused me no problems at all, with identical measurements within the variability in TDS of my water. I did try putting 1/4" fittings in my 3/8" lines by use of couplings and so on, but this was a lot of trouble and gave identical readings to the 3/8" "T" fittings. Conductivity technology is really well-established, gives reliable results, and these meters do a good job of implementing the technology in RO water purification systems. Its really convenient to have a permanently mounted measurement arrangement to monitor performance. The meter will work with any RO system, not just the one I have been using. I recommend installing these right from the start. Review: Great TDS meter! Love it love it love it. - See headlines ## Features - The Dm-2 Tds Meter Installs On Industrial Systems Such As Car Washes, Window Washing, Manufacturing, And Food Processing - The Commercial In-Line Dual Monitor Is Highly Efficient And Accurate Due To Its Advanced Microprocessor Technology - This Dual Monitor Displays Total Dissolved Solids Levels Of The Feed Water And Product Water With In And Out Electrode Probes - Brand Name: Hm Digital ## Technical Specifications | Specification | Value | |---------------|-------| | ASIN | B000VVYRVQ | | Average Battery Life | 13000 Hours | | Batteries | 2 AA batteries required. (included) | | Batteries Included? | Yes | | Batteries Required? | Yes | | Best Sellers Rank | #103,079 in Electronics ( See Top 100 in Electronics ) #50 in Conductivity Meters & Accessories #2,217 in Computer Monitors | | Color | White | | Customer Reviews | 4.2 4.2 out of 5 stars (118) | | Date First Available | July 13, 2004 | | Display Style | LCD | | Is Discontinued By Manufacturer | No | | Item Package Quantity | 1 | | Item Weight | 8 ounces | | Item model number | DM-2 | | Manufacturer | HM Digital | | Material | Plastic | | Mounting Type | VESA No | | Part Number | DM-2 | | Product Dimensions | 0.7 x 2.6 x 4.6 inches | | Shape | Square | | Size | 4.6" 2.6" 0.7" | | Wattage | 3.00 | ## Product Details - **Aspect Ratio:** 16:9 - **Brand:** HM Digital - **Resolution:** 1 ppm (for 0-999 ppm), 10 ppm (for 1000-9990 ppm) - **Screen Size:** 3.1 Inches - **Screen Surface Description:** Glossy ## Images ![Commercial In-Line Dual TDS Monitor - Image 1](https://m.media-amazon.com/images/I/71p9etz0vAL.jpg) ## Questions & Answers **Q: Why does the description not show the size lines for in and out this unit will fit?** A: Fittings Size (1/4" TEE fittings)In case you need a bigger size fitting 3/8" for example we carry it ,you can search the following item B00TG08TQM H2o4u **Q: What t fittings do I need to put this inline of my 3/4” pex? I’m assuming a few different fittings.** A: I am sort of going from memory, but I bought the white, I think teflon, fittings that are readily available at big box stores like Home Depot and Lowes. I believe the fitting provided is 1/4" so you need a pex fitting that fits the size of you pex pipe, but the "T" piece needs a 1/4" to take the one provided. I don't remember any particular difficulties, but in fact I was attaching to 3/8 white plastic tubing, so I needed a different "T" piece from the one you require. Its all a matter of finding the right "T" piece. I took a quick look, and the pex fittings are all compression fittings, so you might have to put a plastic loop with a t piece in the middle to take this device. Lots of ways to skin a cat. **Q: How long are the cables? And is it for 1/4" ID RO line? Your missing the basics in the description** A: On the unit I purchased, the cables are approximately 45" long. It includes two "T" fittings for 1/4" RO/DI lines. **Q: is this available with 1/2'' x 1/2'' x 1/4'' tee fitting? i need the probes to go to 1/2'' tubing** A: You can purchase 1/2 x 1/2 x 1/4 push-in fitting tees to replace the ones that come with it. I'm doing the same thing with a DI system for my detailing business. ## Customer Reviews ### ⭐⭐⭐⭐⭐ Reliable, accurate, convenient TDS meter. *by R***L on March 9, 2017* I have used a GE Reverse Osmosis (RO) water purification system for nearly 10 years. I have been using a single portable total dissolved solids (TDS) meter to check my water and I have had very little need for this more sophisticated device until things started to go wrong due to the age of the RO system. I started seeing poorer quality water, and thought I needed a set of new filters (RO filter, pre and post filters). It turned out that I needed a new shut-off valve, but on the way to this conclusion I installed one of these DM-2 meters. I now have two of them. Each meter has two probes to measure TDS. I installed two probes on the input and output of the post-filter, and two probes on the input and output of the pre-filter. This arrangement allows the two input probes to measure the TDS before and after the RO filter, and the two output probles to measure the performance of the pre- and post-filters. I have checked the calibration of the DM-2 instrument using a standard sodium chloride solution and it was accurate as shipped to me. The meter and its probes are reliable and stable measurement devices. They use the electrical conductivity of the water to estimate the TDS of the water. My purified water comes out to be in the 3-10 parts per million (ppm) range, and my input is softened well water and comes out to be around 145 ppm. For 5 ppm RO water, this is ((145-5)/145)*100% or 96% RO filter efficiency. This efficiency varies with the type of RO filter in use. When you use this device, its important to understand exactly what you are measuring. It turns out that the output of the RO filter is pretty reliable and stable, but a new post-filter tends to pollute the water with preservatives and other particles that I know nothing about. Hence, measuring TDS at the output of the post-filter might make you think the RO filter is not working. However, as the filter washes through over a couple of days, the TDS will improve. All the while, the TDS from the RO filter itself is usually just fine right from installing the RO filter. These instruments come standard with 1/4" quicklock plastic "T" fittings, which allow the probes to penetrate right into the middle of the water stream. Some of my water lines are 3/8" so I used 3/8" "T" fittings which I purchased separately. As these fittings are a bit bigger than the 1/4" fittings only the probe tips stick into the water stream. This caused me no problems at all, with identical measurements within the variability in TDS of my water. I did try putting 1/4" fittings in my 3/8" lines by use of couplings and so on, but this was a lot of trouble and gave identical readings to the 3/8" "T" fittings. Conductivity technology is really well-established, gives reliable results, and these meters do a good job of implementing the technology in RO water purification systems. Its really convenient to have a permanently mounted measurement arrangement to monitor performance. The meter will work with any RO system, not just the one I have been using. I recommend installing these right from the start. ### ⭐⭐⭐⭐⭐ Great TDS meter! Love it love it love it. *by T***S on August 4, 2025* See headlines ### ⭐⭐⭐⭐⭐ More convenient than my old handheld TDS meter *by S***R on January 1, 2019* My old handheld TDS meter since I installed my RO system retired after some 18 years. (Yes, my kid went to college.) I had an eye for these inline systems for a long time. It's not necessary but you don't need to rinse the meter with enough input or output water to avoid cross contamination. This guy has two electrodes and they are ready whenever you want to take readings. I got a brand new looking meter. The electrodes are solid stainless steel embedded in solid plastic. The T connectors are John Guess, the same as all my connectors in my system. The electrodes are of the correct size so there is no leak. I don't even want to mount the meter. When I need to take a reading, I just turn on the power button, read the current display, and press the button for the other reading. So convenient. ## Frequently Bought Together - Commercial In-Line Dual TDS Monitor - HM Digital TDS-3 Handheld TDS Meter With Carrying Case, 0 - 9990 ppm TDS Measurement Range, 1 ppm Resolution, +/- 2% Readout Accuracy - HM Digital C342 TDS and EC Calibration Solution, 342 ppm (NaCl), 90 ml Volume, Transparent/Blue --- ## Why Shop on Desertcart? - 🛒 **Trusted by 1.3+ Million Shoppers** — Serving international shoppers since 2016 - 🌍 **Shop Globally** — Access 737+ million products across 21 categories - 💰 **No Hidden Fees** — All customs, duties, and taxes included in the price - 🔄 **15-Day Free Returns** — Hassle-free returns (30 days for PRO members) - 🔒 **Secure Payments** — Trusted payment options with buyer protection - ⭐ **TrustPilot Rated 4.5/5** — Based on 8,000+ happy customer reviews **Shop now:** [https://www.desertcart.hr/products/6991115-commercial-in-line-dual-tds-monitor](https://www.desertcart.hr/products/6991115-commercial-in-line-dual-tds-monitor) --- *Product available on Desertcart Croatia* *Store origin: HR* *Last updated: 2026-07-05*