VIVOSUN Digital pH and TDS Meter Kits, 0.01pH High Accuracy Pen Type pH Meter ± 2% Readout Accuracy 3-in-1 TDS EC Temperature Meter for Hydroponics, Pool and Aquarium, Yellow Blue, UL Certified

After reading several reviews on this and other similar models I decided on this two pack PH and TDS. I recently installed a reverse osmosis under kitchen sink with a tds digital display and wanted another way to check its accuracy along with what ph the RO water was putting out. Item arrived quickly and after reading instructions I decided to give it a test. Batteries were already installed and additional batteries were included so that and they both were already calibrated so two pluses from the start. I filled a glass with reverse osmosis water and another from bathroom sink. Tds for bathroom were 107 compared to RO water of 9. This is the same reading my RO system shows so I assume its pretty accurate. Next I tested the PH. Ro water was higher than bath sink water but this units numbers jumped around a bit. Although the numbers did not display steadily i was able to get a good reading and am pleased with the results. For the price I find the two units a great bargain and much better than the water test strips I was using. After my initial tests I highly recommend these products as they appear to be accurate and easy to read.

The ppm meter comes ready to use, the pH meter needs to be calibrated before use with the provided materials. It works well and is pretty fast.

The TDS meter works very well, especially considering the low price — it gives quick and reliable readings. However, the pH meter takes a bit longer to stabilize and provide an accurate measurement. Overall, it’s a useful and affordable kit for basic water quality testing, but be patient with the pH readings.

Use this for making my espresso machine water. Very easy to use to measure TDS as i am adding minerals back to a distilled water gallon

The pH meter ended up being basically useless. I carefully followed all instructions. It took a lot of time and frustration to successfully 3-point calibrate it. After calibration it seemed to be partially accurate but it would take 2+ minutes to provide a reading. Even then, it would start about 2 points above the real reading then slowly keep drifting downwards at a rate of roughly 0.01 per 1-2 seconds. It would never “land” at a reading. After a week of use I gave up on it and just went back to using chemical pH tests because those only take a fraction of the time to get a ballpark reading. The TDS meter was a little better. As I said before I followed all instructions carefully regarding usage and proper storage. For the first month of regular usage (used 1-3 times per week) it worked great and exactly as expected. Then the temperature readings became unreliable. I have other digital thermometers to compare it to and this device was consistently off by about 5-10 degrees fahrenheit which made it useless at that point. The TDS portion of the blue meter seemed to be accurate and mostly worked until the end of the 2nd month. Then it would randomly behave strange. I would test the same sample of water 3+ times over 10 minutes and the ppm reading would fluctuate by 10-40 ppm. Or sometimes I would test two samples of water from my fish tank taken about 24 hours apart. It would read out exactly the same as if the meter was “frozen”. I know that isn’t accurate as the 2nd sample would be taken 24 hours later after a fish feeding and a plant fertilizer dosing. So it’s highly unlikely that it would give an identical reading for the 2nd sample.

The VIVOSUN digital pH meter is easy to use and gives quick readings, which is convenient for basic testing in hydroponics, drinking water, or pools. The pen-style design is compact and portable, and the display is clear and easy to read. However, the accuracy can be inconsistent unless the meter is calibrated frequently, and the readings may drift over time. Build quality feels somewhat lightweight, and for more precise or professional use, it may not be fully reliable. Overall, it’s an acceptable 3-star product for casual or occasional pH testing, but it may not meet expectations if you need high accuracy or long-term stability.

Accurate, it comes "pre-calibrated" for accuracy, though they also include 3 little foil packets of buffer powder to re-calibrate. But the 3 packets are for different pH levels. You can do 3 calibrations for 0.01 accuracy, but I would have preferred 3 packets of the pH6 buffer.

Forgot to right review but very good cheap devices I mix my plant food with them they work well

La calibration est simple. Par contre, par rapport à une sonde témoin, il est extrêmement lent. Il faut compter presque 10 minutes pour que le pH final soit affiché. Il faut donc le mettre longtemps pour à avoir le bon pH. Après 6 mois et une utilisation par mois, il deconne complètement. Mauvaise qualité

Arrived not working, tried replacing the battery but no joy so sourced an alternative

I bought this set mainly to check the conductivity of my LC coolant in my Ioniq 5. The items arrived quickly and safely in a solid box. It came with full instructions and even an extra set of batteries. I checked the TDS meter using tap water and got an expected reading of 56 (pure distilled water would be closer to 0) us/cm. I am very pleased with the performance and the value. Highly recommended!

TDS meter are working fine but for the PH meter I personally don’t arrive to fully calibrate it as all the time I do the PH 7 then PH 4 and when it’s arrive to do PH 9 it’s return to PH 7 so impossible to complete the calibration.

Works well