HM Digital TDS-EZ Water Quality TDS Tester, 0-9990 ppm Measurement Range, 1 ppm Resolution, 3% Readout Accuracy,Purple

When buying a TDS tester I suggest that you also get the HM Digital TDS Calibration Solution (342 PPM) to periodically re-calibrate your HM Digital TDS meter or HM Digital Water Quality Tester. It is available through Amazon for around $9.00, and is worth having to periodically check your drinking waters TDS level. This meter performed very well. I first tested the meter with the calibration solution. I took three readings with this solution before measuring tap water, purified bottled water, and Reverse Osmosis filtered water. All readings were taken at a room temperature of 75 degrees, but water temperature was not tested, nor was the PH of the water.Calibration Solution: Reading #1 gave 328 PPM, #2 gave 331 PPM, #3 gave 336 PPM. I followed the direction each time I took a reading, and gave the TDS meter several minutes to air dry in between readings ( about 5 minuets) During this time the TDS solution was covered.. I noticed that each time I tested the solution the reading went higher. So I took two more readings following the same procedure as before. Reading #4 330 PPM, Reading #5 329 PPM. I have to think that the meter is fairly accurate. Readings were all in the plus or minus 3% range.Next I tested purified bottled water Reading #1- 3 PPM, Reading #2- 5PPM, Reading #3- 3PPM.Then I tested Reverse Osmosis water after changing the filters two days before this testing. My R/O test range was between 15-22 PPMRegular tap water is a very "Hard" water out here in the Desert Southwest. It ranged from 185 to 240 PPM. Pretty awful . We don't drink the water out of the tap unless we have to.The result show a fairly accurate and good TDS tester. I believe some of the variances in the readings may be attributed to water temperature and or PH or both. Even though I gave this tester a 5 star rating I would invest a few extra dollars for the model that has the (ATC) automatic Temperature control compensator , and the PH tester.This meter did perform as advertised , and performed well. It is worth the price, and for now I'm happy with it. Hope this helps you make a decision.

The Testers work great! Very simple and straightforward!

This unit worked exactly as I hoped. I read the reviews and bought the slightly more expensive unit with temperature compensation. This is well worthwhile to ensure consistent measurement over varying water temperature. The unit is very easy to use although the button labels are hard to read. There is a quality reference scale printed on the back of the unit which is very useful. I verified that our tap water impurity level was around 200 which is ideal and aligned with a separate water test I did (see separate review). I also tested our "Perfect Water" filtration unit (see separate review) which showed a measurement of less than 10 (i.e. that the mineral content of our tap water had been reduced from 200 to less than 10 by the four stage filter) thus proving that the filter was working perfectly and also giving confidence in this great little measuring device (the filtered water tasted great but that isn't an indication of quality).If you are fitting a whole house humidifier with electric conduction steam generation, the water MUST be above a minimum level of hardness (i.e. the house water should not be softened) for these to work. This device could be used to verify that your water is suitable for this type of humidifier.Note that this device will NOT test water safety, it only indicates the levels of minerals in the water (i.e. hardness). You should still do comprehensive water testing if you are in any doubt about your water quality.

I purchased this product after reading positive reviews by people who have hydroponic gardens. I decided to try it for my aeroponic garden and it has made my life so much easier. I used to judge if I needed more or less nutrients based on how my plant leaves looked, but with growing many types of vegetables this was anything but accurate. Now I know what my ppm range should be and I just test it once or twice a week and add nutrients or water accordingly. This has taken all the guesswork out and my vegetables have never looked so good!Update 6/2016: After having my first tester since 2013 a piece had worn off and I needed to replace the tester. Since I liked it so much I purchased the same one again in March. I've only used it a handful of times and have had it for less than two months and it stopped working. I was hoping to send it back and have it replaced but unfortunately they have a 30 day warranty. Very disappointed.Update 7/2016: I contacted the vendor (HM Digital) directly and they were very helpful. I returned the tester to them (cost me $2) and they agreed it did not function properly and sent me a new one, which works perfectly. I'm happy with the resolution.