VIVOSUNDigital 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.

These work great for my hydroponic vegies. Easy to use and a great price.

Takes forever to read but good value for the price

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.

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....

Tested these and they read perfectly. Definitely worth the money easy to use.

Fast shipping, it’s gonna help me feed my plants, it’s an awesome price too, perfect for my budget. I would buy this product again if I ever needed.