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.

Great value for the money., easy to use, but would like more information on the readings. Very easy to use Compared to other products this was a great buy. Shipping was fast., good value.

Vivosun Digital pH and TDS Meter receive a 5-star rating because of the customer service, and the products. The pH meter was not working when we received it. I contacted Vivosun and they offered a refund or replacement. I went with the replacement and received a new pH meter the next day. Both meters are working, now I just need to adjust the pH in the water I am giving my herbs so we can all be happy.

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.

If you calibrate ANY PH meter using the mix it yourself "calibration" solutions, accuracy will be a crap shoot. Consistancy may be excellent, but without another properly calibrated meter to test it, you will have no clue what PH your homemade "calibration" solution actually is. I just purchased this meter set, and in the process of calibrating it, discovered the distilled water I use was ph4 and even below! I have the "other" style, cheap, manually calibrated meter, that has proven very stable for me. So I rechecked it in a *premixed* 7.0 "Standard Reference Solution", then used it to test the accuracy of this relentlessly popular, yet poor example of an auto calibrating, ph testing system. I say "system" because the meter itself may be accurate enough for most applications. The mistake is assuming all distilled water is the exact same ph, or that the included powder magically compensates for variations in ph, of whatever water Mr Joe Blow decides to buy, and hits the target ph within two decimal places! Wow! A miracle! The first red flag is the solution instructions make no mention what the ph of the distilled water needs to be. My 4.0 water mixed with the 4.0 and 6.86 powder, resulted in solutions of 3.3 and 6.0 respectively. I didn't bother testing the 9.0, and continually rechecked my "other" meter throughout the experiment. I would encourage 4 & 5 star reviewers to check your powder based test solutions against the real thing. I would advise buyers to plan on not using the included powders. Buy premade Standard Reference Solutions, and since it is so easy, store & calibrate the meter every time in those SRS. I would advise the manufacturers to drop the powder fiasco, and change the auto calibration standard to 7.0. In summary, the DIY calibration solutions are a joke, as are the auto calibrating ph meters using 6.86 instead of the 7.0 standard. Makes it too easy to trust the included powder, vs buy premixed 6.86 SRS, and realize how unstable the calibration is...I *think* it's available...?

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

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