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, Black White, UL Certified

Essential tool reasonably priced

Vivosun Digital pH and TDS Meter receive a 5-star rating because of the customer service, and the products. The pH meter was not working when we received it. I contacted Vivosun and they offered a refund or replacement. I went with the replacement and received a new pH meter the next day. Both meters are working, now I just need to adjust the pH in the water I am giving my herbs so we can all be happy.

I have fully completed my review and as mentioned in other comments, the calibration issue is not something amateurs can easily do and there is a packaging and manufacturing issue in the calibration specifications. The pH that comes out of the package that is pH 6.8 shows 4.00 and the pH that comes out of the 9.18 shows 6.86. There is a packaging error. In short, the device is not bad but the calibration process is a problem. It would be great if technology could find a solution to this issue.

I have a scientific grade PH probe that has been in continual use on a 65 gallon discus tank for 6 months and it was time to recalibrate as part of routine maintenance. After 6 months of use, probe had barely drifted. I used PH 4.0 and PH 7.0 calibration fluids. Probe was spot on with the 4.0 and read 7.1 with the 7.0 so it only needed a very minor adjustment to bring it back into perfect calibration. I used this probe as a comparison with the VIVOSUN. The VIVOSUN readings straight out of the box were pretty far off. Measuring the PH 7.0 solution, the VIVOSUN reported 7.6. Measuring the PH 4.0 solution, VIVOSUN reported 3.65. I calibrated the VIVOSUN using the provided powder for all 3 PH solutions provided as this should provide the most accurate readings per the instructions. Immediately after calibration, I poured fresh 4.0 and 7.0 solutions and the VIVOSUN results were at least .5 off in both directions. Poured fresh solution AGAIN (after rinsing probe in RO water) and once again results were way off (but different from the results it just reported from the first fresh solution pour. I then compared with test strips and the test strips matched the results from my scientific probe. In short, do not rely on the pH meter and I would go so far as to say you need to throw it in the trash ASAP. The TDS meter is also flawed. There are 4 modes of display, according to the instructions whichever mode you choose will remain the default until you change it.. (e.g. Power it off today and tomorrow when you power it on, it should default to the mode it was in when it was powered off.). It does not do this. Not only that but in the middle of taking a reading, it will just randomly switch from measuring PPM to EC or from Celsius to Fahrenheit. I don't have anyway to validate the EC or PPM readings but judging by what I can validate, I would not trust it in any way, shape or form.

I can honestly say this little pH meter (black Vivosun) has exceeded my expectations. For such a low price point, I figured there would be considerable issues with sensor drift requiring constant calibrations however this little guy has always been within .1 pH when checking prior to the calibrations I have periodically performed over the last few months. Proper rinsing and storage as well as frequency of use are also important factors when maintaining accuracy with a pH meter however the quality of the sensor is also part of the equation. With that being said, this Vivosun pH meter appears to be well made. I would always recommend periodic calibration of a pH meter if you are relying on its accuracy regardless of the manufacturer. The probe is easy to use and easy to rinse after use eliminating any hassles and the removable probe cover provides protection during storage. The readings quickly stabilize which has also streamlined my testing process. Overall, this has been a great value and I would recommend especially if on a budget.

pH: I tested distilled water . Distilled water is ideally neutral (pH 7), but becomes slightly acidic when exposed to the air because it absorbs carbon dioxide, forming carbonic acid, which lowers its pH to the slightly acidic range of about 5.8 to 6. (AI) The meter kept shutting off, but turning it back on, it picked up where it left off. After about 5 times it settled down to 5.6. It's a little unsettling to turn it back on over and over, but the end result does make sense. My tap water is 8, so this is good news to me because most vegetables and stuff like it around 6 to 6.5. Aquariums need below 7.6 which is the beginning of an Alkaline pH. I think adding the distilled water is a better way to lower the pH than adding chemicals. Just a personal preference.

Are these things cheap. Of course they are. Are the accurate? Yes. Are they laboratory accurate where .001% is required? Not even close. .1 close enough? These will be OK. They are easy to calibrate and hold the calibration. I bought some other more expensive PH meters and they were not as good as these. I bought some extra calibration powder to check and calibrate and they hold the calibration a while. I use them for boiler water and they are fine for that.

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.