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 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

I had recently bought a TDS meter ( HM Digital TDS-3 Handheld TDS Meter With Carrying Case, http://www.amazon.com/gp/product/B000VTQM70/ref=cm_cr_ryp_prd_ttl_sol_11) for home use.This 342 ppm TDS calibration liquid is must for the meter. Although the meter description says it doesn’t require calibration but it is always good to calibrate it.It comes in a very sturdy plastic bottle, which is leak-proof.You always need at least two calibration points to correctly calibrate a metering/measuring device. Therefore, I also bought another calibration liquid for 1000 ppm (HM Digital 1000ppm TDS Calibration Solution: http://www.amazon.com/gp/product/B001FD6WZ8/ref=cm_cr_ryp_prd_ttl_sol_0 ).Many people have mentioned that you can make the calibration liquid at home by dissolving a known amount of sodium chloride in water. I would like to mention that its wont be a good idea. First, the water itself is not pure and you don’t know what is its PPM value. Second, and important, weighing 0.1 to 0.5 g at any weighing balance we have at home is impossible. So spend some money and buy it. You wont regret it.I calibrated the meter with bot solutions and then measured a few liquids f known ppm value and the reading I got was fairly accurate (within 5% of actual).Always clean you TDS meter thoroughly before dipping it in the calibration liquid. Else you may change the concentration of the liquid, which will lead to wrong reading from your test water sample.!!!!!!! I STRONGLY ADVISE TO BUY THIS CALIBRATION LIQUID WHEN YOU BUY A TDS METER !!!!!!

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

This was perfect for what I needed, which was to calibrate my HM Digital TDS-3 EC meter.

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 have a TDS-4 meter (the $20 one), and although HM Digital says they are calibrated at the factory, I got the EC calibration solution anyway with my new meter just to be sure. What I found was my new TDS-4 was off by as much as 10%, and I only found this out through calibrating with this solution!So if you purchase a cheaper TDS meter, it is good for peace of mind to get the calibration solution right out of the gate to be sure you are getting the correct readings!Some things to point out:-- The solution comes with a sealed top, so you don't have to worry about not getting what you paid for. I wondered about that when I ordered it - would the top be factory sealed? It was.-- You may want to consider how you are going to use it - if you just dunk your dirty "polluted" meter into the originalcontainer, then you will have polluted the whole batch of NaCl solution. I poured off a small amount into a small glass container that was pre-washed / sterilized with alcohol, and also cleaned the tip of the TDS meter with alcohol.-- Whether you pour the used solution back into the original container is up to you - I did not. I wanted to keep the original solution / container as pure as possible!

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