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

Great product! Wish it came with a few more packs to recalibrate instead of just one set but other then that 5 star product!

I use it every watering, the ph meter stays calibrated for a whole grow pretty much give or take the usage

The pH meter isn't as accurate as the $50 Apera PH20, and it's a bit awkward to calibrate. Granted, the variance is just a few tenths, but when measuring pH in your water, nutrients, and runoff, a few tenths is a lot. I can't speak to the TDS/EC meter accuracy, as I have nothing to compare it with.

Perfect 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.

I love vivosun products. I have a 3x3x6 filled with all vivosun. Duct,light, fans, hydrogenator, cam, and I picked these up to ph my water. It had a weird white calcification when I opened it for the first time.

Very easy to use. Comes calibrated. I haven't had to calibrate it yet. Been using for about 2 months daily. Battery seems long lasting, quality is good. I don't think i"ll ever calibrate it because I can just put it into new soil, see what the number is, then adjust my plants based off of that.

Would recommend. Works great.