VIVOSUN Digital pH Meter 0.01 Accuracy Pen Tester for Water Hydroponics

This product works as advertised. You have to calibrate it first using the provided ph packets but once you do that it is good to go and offers accurate reading. This product assembly and price range makes for a nice introductory ph meter as opposed to a more premium, and also costly, assembly, yet it is still so much better than a manual ph test strip. I would recommend this product to anyone looking for an affordable digital oh tester. I like the vivosun brand and the products they have offered so far.

This is the second of these PH meters I've purchased. There are a number of negative reviews, so I was a little concerned but went ahead and order one. The first meter calibrated easily and (apparently) accurately. I used the three point calibration, then tested my fish tanks and compared the reading to the drop type ph test kit I had been using. It was spot on as close as I could tell with the test kit. I used the meter for a week, every day on several tanks as I changed the ph. It tracked these changes as I would have expected it to. It worked very well for me so I ordered a second PH meter. (I have fish tanks in two locations.) I then used these two meters side by side. They vary from each other by 0.10 points. The second meter did not calibrate as easily as the first, and the calibration was off slightly. I will try recalibrating, but it's as accurate as I need now. I'm very satisficed with them and would recommend.

Please understand I rarely give reviews but I felt led to warn potential users. It simply will not calibrate. I have received multiple errors. I've gone through the trouble shooting steps and still no success. Changed the batteries, rinsed it with plain water to retest, made sure I didn't go over the max line, turned it off/on and I even measured the water to 250ml. Frustrating to say the least. Find another user friendly product

It helped me get the pH I wanted for my plants. It appears to be well constructed. I really like how the display lights up upon first use, though I wish it would stay lit because the first several seconds are never accurate, you have to let it calculate and settle for about 60 seconds. Photo is of my pen in my DIY storage solution after 24 hours. WARNINGS FOR ALL NOOBS: Do not trust or test any of these types of products for water resiliency. Do not drop them in water. Only the first 1-1.5in is supposed to ever go into a solution. It shows this on the piece of paper that comes with the product. To avoid contamination do not test directly in your solution. Pour some solution into a small glass to test. STORAGE: as soon as you open up your pen, store your product in electrode solution. If you are not smart: buy a bottle of solution on Amazon. If you are smart you can make your own: buy on Amazon a 1lb bag of KCL, an AMIR portable scale, and some graduated pipettes, and de-ionized water from the grocery store (mine had a machine I had to run to fill up with freshly filtered water). I tested distilled versus reverse osmosis and the RO water was closer to 7.0 so I used this for my solution. Then weigh out and mix 7.45g KCL in 100mL of your neutral water to make 4 molarity (4M) KCL solution. Boom. You now have a lifetime supply of storage solution. I found that through a quick Google Search (Omega Engineering's pH electrode PDF). Pull the pen out of solution, rinse off with a neutral water, put pen in a small glass with 1 inch of solution to test, record value, rinse off with neutral water, place pen back into storage solution. I gave it four stars for several reasons: 1) "Very accurate". Meaning, it helps me get closer to the pH I want by increasing accuracy within a 0.1 to 0.5pH range. I don't trust the factory calibration because I have already used it with some variance. I think as soon as you take an electrode out and use it on one source of water you have impaired its ability to test another solution. For analog chemical reagent tests, I have used a general purpose hot tub kit and a General Hydroponics reagent test. It beats the hot tub kit by a huge margin (since that reagent test only tests from 6.8 to 8.2), and the GH reagent kit by a margin of 0.5-0.9pH. E.g. GH was showing 6.5pH, actual 6.2 (with this pen). Then I adjusted pH. GH showed 5.0. Actual was 5.8 (with this pen). 2) "Cheap" - can't find anything cheaper. 3) It only includes 1 calibration test kit and no reference of where to get more. I would pay $5-$10 more to have a bundle of calibration packets added to my order. 4) The display light does not stay on and there is no "light" button.

Received on July 23rd 2025. This is lightweight, user friendly and easy to calibrate. It came with extra batteries and 3 packets of pH Buffer Powder. The design is simple, nothing unnecessary. However, it takes a minute or so to get a reading. Much slower than I would like but for the price you can't exactly complain wholeheartedly. I am slightly worried about the standing quality after some time. I'll update my review with the quality, how long it works, the batteries life, and if anything changes.

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.

Although it may be a little delicate to calibrate upon first time using. Insure solution temperature is ~75 degrees F. Measure out 250 ml distilled water. Insert the meter into a cup pour into another cup until you reach the line on the meter. Turn meter on holding down the calibrate button for 5 seconds then release. Press Cal button one more time. I did not get a display showing "cal" like some of the YT videos. This generates confidence in the meter concerns. However, I had a lab tech at the university check the calibration in a buffer solution of 7.0 and the meter showed 6.97. First pH meter that works and provides accurate results.

Very easy to use and calibrate returned on that was bad and they replaced it in one day!!!!

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

Macht seine Aufgabe gut.

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

calibration is hard but when it's done it's good

Works great but do not like that have to calibrate it