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

They seem to be working okay although I don't like how they have to be calibrated. But they do work.

I've found these to be very accurate and easy to use. So far I've used it to test our tap water, filter water, aquarium water, and spring water on our land. The ease of the devices is really top notch. I'd highly recommend to anyone interested in a quick look at true water quality.

Ok so at first i was very upset with the ph meter because it was all twacked out. I attempted to calibrate it the first time and made it worse. After doing a calibration on it a second time, now, i can say it work ok. It's still not highly accurate but close enough for my plants and anything else i might want to use it for. That being said, if you do buy this product, be prepared to do some calibrating, probably somewhat often. It states when ph meter electrode its in dry air for long periods of time it will need calibrating, frequent use of will need calibrating, the CAL button was pressed and the electrode was exposed to air for a while, it will need calibrating. So yea, it works, but will need calibrating.

Accurate and easy to use. I've been using the liquid test tubes for this parameters. And these 2 = game changers for me.

So I bought this set wanting to try out actually tracking and adjusting my pH and EC of my nutrients for my little indoor hydro-farm. Like most people, I didn't want to spend a lot on my little hobby so I figured I would give this product a try as I actually enjoyed some other Vivosun products.I'll start with the TDS/EC Meter. It is actually decent and appears to be pretty accurate right out of the box. I've used it for a little while and it remains to be acceptably accurate so far without any issues. Good to go, this one I'm pretty happy with and will continue to use at least for now.Next I'm moving on to the problem child, the pH Meter. Wow. Where do I begin. I started off trying to figure out how to calibrate this little thing as the instructions drastically varied from all the calibration videos available online for it. Maybe they changed the method but once I figured out how it wanted to be calibrated I went through the steps and all was good. I tested it a number of times using various testing liquids and it was pretty spot on (at least within acceptable limits for my hobby, not anything that needs to be precise though). So I mixed up some of my nutrient solution, cleaned the pH and TDS meters as advised to in the manual and put them away safely. Fast forward 1 week, I pull out the pH meter and dip it into a cup of distilled water and it tells me that it has a pH of 10.3! Far from the value of 7 I was expecting to see. So I pulled out my other pH balanced liquids to test and every one of them was extremely off from what it should be. It completely lost ALL calibration after one use, and one week of storage. I'm sorry but that means I need to calibrate this thing every time I turn it on? And they only supply you with one set of calibration powder that isn't to be re-used? Absolute and complete garbage. The calibration costs for a year would be well into the hundreds a year for a $10 meter! Absurd. This is a product you should definitely skip buying. Buy yourself a 14-sided dice and give it a roll, it will give you a more accurate guess on your pH level than this thing every will. I would return it, but I was not thinking and threw away the packaging already.

Ill start that I have a PH/EC continuous monitoring system for my hydro reservoir from Hanna for 15 years and its 100% accurate, I calibrate it once monthly with lab grade calibrating solutions. I bought these inexpensive handheld PH and PPM spot meters because my expensive PH/PPM handheld meter also from Hanna stopped working and I needed a handheld spot check meter, and I was being cheap, I've been unable to get the VIVOSUN PH meter to calibrate or read correctly and I've tried 3-4 times with my lab grade calibration solutions so its pretty much useless, but the PPM handheld meter has been tested with calibration solution and against my continuous monitoring sys and works correctly showing a correct PPM, soooo the PH meter doesn't work but the PPM meter does, a new dual PH/EC Hanna spot meter would be my recomention but as stated you get what you pay for folks....

Great value for the money, I have owned a few of these and this one is definitely accurate and built well. It comes with a TDS meter as well, this is less important for me but it is nice to have. I like the size and the fact that it adjusts for the water temperature. It has a nice backlight that works great, just don't dip this thing too far into the water. Super easy to use though. The calibration at first takes a little bit of time but once you get through that, using it as a breeze. Setup should only take about 5 minutes, make sure you have distilled water when you start though.

Its really good at doing it's job. I've had this for about 3 months and have not needed to Calibrate it yet. Trust me this is much better than getting an automated one, the accuracy is superb.