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

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.

Works as advertised. Comes with buffer packs to calibrate. Would 100 percent buy another when this ones life is up. Thanks yall! Vivosun is my go to grow store online. Always what i expect! Love yall!

Most likely this was a returned broken meter does not calibrate after many attempts only 6.86 on any test the same thing the 9.18 comes up and says 6.86 the 4.01 comes up and says 6.86 the 6.86 says 6.86 but it will not calibrate at all watch out they'll send you stuff that's broken. When you press the calibration button the digital takes off past 10.0. Just a piece of junk. Distilled water at the exact temp, and washed off after each check.

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.

An inexpensive yet reliable meter!

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.

Best pH pen I have ever used. I’ve had the cheap ones before but they never calibrated properly. This one was perfect on the first shot. Vivosun may be my new favorite brand for growing supplies!

Good, useful.

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

Cheap and effective

Funktioniert gut sogar mit Leitungswasser

Works well

Buscaba un medidor de ph con poco tiempo para comparar precios, y sin aparatos de medida para comparar su exactitud. De los 3 sobres de calibración sólo usé 1 (el de 6.68, que es lo más cercano a lo que quiero medir) Curiosamente, cada vez que lo enciendo empieza en 14...y tarda unos 2 minutos en llegar a la medida. Las instrucciones "regulinchi", pero en Youtube hay tutoriales magníficos. Creo que he pagado 3 euros más por la marca (por eso no le doy 5 estrellas).