HM Digital C342 TDS and EC Calibration Solution, 342 ppm (NaCl), 90 ml Volume, Transparent/Blue

It is good to have this to calibrate my TDS tester. I have never needed to calibrate my tester but decided to make sure that it still works after 3 years ilof periodic usage. Only issue is the cost and there is so much of it that I won't need to use again for a few more years.

I have used this to calibrate my to different TDS meters. One I cannot calibrate but it only reads a little over the stated TDS on the bottle. I use this to calibrate my TDS meter that I mainly use to keep RODI filters in check for reef tank. So far it has worked prefectly and would definatly recommend to someone else or buy again.

I thought a little too expensive for what it is, but seems the cost is much the same elsewhere...

Great product to insure TDS meter results are accurate and reliable. A necessity. Recommend

Readings were spot on, easy to use and does exactly what it is supposed to. A little more expensive than some other choices, though if it is accurate, that's all that really matters. Great purchase

I had a lot of problems doing calibration with my HM DIGITAL TDS-3 METER was getting 320 then 411 then 422 then 511 then 477 readings. I thought something was wrong with the solution but I have since found out that the HM Digital TDS-3 I bought is a knock-off FAKE and so it is not the solution like you said, it's the meter itself. I contacted the manufacturer HM DIGITAL and sent them photos of the meter Amazon shipped to me and they instantly said it was a FAKE.NOTICE TO EVERYONE: A real original HM Digital TDS-3 meter will have these traits:1. when you turn the meter on it will show "HM" in the display for a second or two then it will display 000 but it must show HM when you first turn on2. a real one will have 5 bumps on each edge of the front, not just in the photo on description page, but on the actual product itself. if it doesn't have the 5 bumps on each side it is a fake3. it will have instructions how to calibrate in black letters on the back along with a hole and a screw to calibrate it manuallymany amazon sellers have these traits in their photos but when the product arrives it doesn't have the 5 bumps on each side, doesn't have the calibration printed in black on the back with a screw to calibrate, and doesn't show "HM" when you first turn it on across the screen. the HM will be big and easily see when you turn it on.BTW: MANUFACTURER CONFIRMED THIS IS THE REAL HM DIGITAL CALIBRATION SOLUTION

The numbers were wayyy off so not sure how to read anything else now. Showing my bottled water level too to compare.

I took the lid off and put the bottle in the microwave for 8 seconds, then I used a laser temperature meter to check temp. At room temp of 69 degrees, my TDS meter read 302 in the solution. When I heated the solution up to 77 degrees. My meter read an exact 342 ppm which is perfect. To get an accurate reading, the solution must be at 77 degrees.In my tests, for each 1 degree the solution is off from 77 degrees. There is a corresponding 5 ppm error in the results.