HM Digital DM-2 Commercial In-Line Dual TDS Monitor, 0-9990 ppm Range, +/- 2% Readout Accuracy

The HM Digital fit and works immediately since it is already calibrated!

Very accurate and easy to install. I have this under my kitchen sink hooked up to my reverse osmosis water filter system and now I can see e before TDS of the incoming water, and the after TDS of the filtered water. It shows my incoming water at 193 TDS and after the RO filter at 6 TDS. I can monitor when I need to replace my filters as opposed to just changing them because they say so. This little gadget will save me money on filters and will pay for itself over and over again. A must have because not only is it cool, but saves money too.

I grow plants with RO water, and so you have to regularly check your water to make sure the filter is still working. Once you start to see your PPM climb, you know that the filter's starting to go bad and you need to change it out. It's usually kind of a pain to bust out another meter to just check your water everyday, and also you're checking water at the bottom of your tank, not the new incoming water. This meter lets you check the water as it's entering your tank at the price of a button, so that's nice.

Since Culligan was coming to fix something I had them add the TDS meter. Looked easy to install. They also added the pressure gauge at the in take area. The out take reading was captured after the carbon filter which had a larger pipe. The digital read out is easy to read. Wish there was an alarm or Wifi to notify me. Culligan doesn’t offer any product that does this.

First unit ordered I received DOA. It showed a lot of scuffing like it was a second or return, then again maybe just Amazon's TERRIBLE packaging. Literally the meter was placed in a Ziploc bag and dropped in a box. Returned and received a 2nd unit, in same condition I might add, i.e. scratched, scuffed, poorly packaged, no padding no nothing... but I digress.Second meter works and the probes are within 9 PPM of one another for the same water sample. I call that respectable and within the ± 2% accuracy. However, this unit is supposedly calibrated at the factory. It's not and not even close to calibration, >100 PPM off to a known calibration solution of 400 PPM, that's over 25% inaccuracy out of the box!! Should have returned it just for that fact alone.As far as this being a commercial unit, not even close. I have access to my companies fluid dynamics lab and water analysis. I can confidently say this is cheaply made, in fact low end of residential use. Poorly fitted housing with plastic membrane switches. Don't expect good water resistance on the housing nor more than a few thousand cycles on those membrane switches before cracking allowing yet another chance for water intrusion.In closing, buyer beware. While on the cheap side and likely not durable over the long haul this meter meets my needs for measuring input/output of a resin ion exchange bed. Your meter's calibration IS questionable right out of the box so unless you have access to known solutions you'll be buying a calibration solution too. And seriously no AC power cord option?!?Time will tell if the this was a wise investment or expensive mistake.June 12, 2018 Update - Returned the 2nd meter. Inaccuracy and inconsistency issues persisted such that I could not trust readings at any point without calibration to a known solution first. Defeats the purpose of an inline meter. Switched back to a handheld Hanna Instruments. Not as convenient, but at least accurate and dependable.June 19, 2018 Update - Down to ONE STAR. So I waited over a week since the return meter was delivered. Get this... I was debited a $6.12 from my purchase price. Contacted Amazon customer service and explained I was not fully credited for the defective product. Customer Service states the debit was a RESTOCKING FEE!?! For defective product!?! Umm, NO! I was not notified of this debit, no explanation as to why I was debited... I simply state, this is not going to happen. After pressing the agent for specifics on how restocking fees apply to defective product the agent says I'll be credited back the $6.12 that I was debited. But still can't explain how or why I was debited and he's (Benedict), "Sorry for your confusion." Seriously Benedict... I'm confused?? This chat conversation took 24 min to get handled before I found resolution. I kept a copy of the transcript, I'm pretty sure there is legalities to debiting one's account without notification or justification.I thought wow, this product ships from and sold by Amazon.com. Unbelievable!! Thanks Amazon.

LOVE It....perfect install on the Input and Output to monitor your Reverse Osmosis membrane performance. Unit can be easily calibrate by Pressing either In or Out for about 3sec to calibrate either Input or Output...it then goes into CAL mode on display....press either In or Out to goes to calibrate the measured number...pressing In or Out will make the TDS number Up or Down to 352 based on the NaCl calibration solution of 342ppm. When you done...pressing On Off button one time to lock in the calibration...Display will show END and that is all you have to do to calibrate the unit. Very simple.

This is a must have if you run a RODI unit. Without this meter I’d never know what my filter is filtering. It’s one of the best around and very reliable

Am not sure what's going on, this PPM version felt inaccurate. I have to investigate further.I have a their pen type TDS meter. That has been excellent for a long time.The first DM-2 unit I got was 7 years ago with uS measurement. It was good. Inconvenient not to have PPM natively displayed.Ordered the DM1 to see if that's a better purchase.Accuracy seems to be a problem in some reviews.

Excelente producto

Nice unit. Auto off is nice and good back light. Seems accurate after my ro system but I don't have anyway to check it.

Bueno, he visto que la medicion varía, asi que mejor hay que dejar correr agua y ver despues el monitor

Funciona bien y fácil de instalar, únicamente que puede necesitar un factor de corrección