VIVOSUN Digital pH Meter, 0.01pH High Accuracy Pen Type pH Tester for Hydroponics, Household Drinking, Pool and Aquarium, Yellow, UL Certified

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.

Looks great, easy to keep clean, seems accurate, everything I was looking for

Meter comes w/ single use buffer packet used to calibrate the meter. Meter requires periodic recalibration. But the company does not disclose the contents of the buffer packet nor where they may be purchased. Not in the instructions and not on the company website. Indeed, instructions say to contact the company if there are any problems but don't disclose any contact info at all. So if you buy this meter it will be good until it needs recalibration then it's just another piece of useless junk. This meter does not appear on the company website at all. Take a hard pass on it.

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.

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.

Accurate, it comes "pre-calibrated" for accuracy, though they also include 3 little foil packets of buffer powder to re-calibrate. But the 3 packets are for different pH levels. You can do 3 calibrations for 0.01 accuracy, but I would have preferred 3 packets of the pH6 buffer.

Very good.

Works just like it says , a must need for growing

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

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

Works well

Esperaba fuera algo sumamente sencillo de usar, y necesita ciertos insumos que los trae incluidos pero al terminarse no se donde los podré conseguir. No supe como usarlo.

Produto correto para quem não precisa de muita precisão. Dá para fazer a calibragem de 1 etapa (pH neutro), mas não de 3 etapas (com pH ácido e básico), apesar o produto seja previsto para isso. Segui exatamente o manual, assisti também vídeos, mas nada: o produto nunca entrou em modo de 3 etapas de calibragem. Pode ser que minha caneta esteja com defeito.