Calibrating PH and TDS Pens

This blog will explain the importance of calibrating your HM pH and TDS pens. 

All digital measuring equipment should be calibrated often to ensure the probes are clean and in working order every time they are used. 

Manufacturers suggest calibrating your digital measuring equipment once a month. I like to be 100% certain every time I use my pH and TDS meters and calibrate them before every use. Pens, more so than stationary meters, should follow my recommendation as they can easily become uncalibrated due to less than favorable handling practices.

Before calibrating your pH and TDS pens, make sure you sit them in some water; tap water is fine.  Give it about a minute before moving onto the next step. 

While you wait you can prepare your calibration solutions by placing a small amount of each solution into separate cups. You will need enough solution in each cup to submerge the probe of each meter entirely. The calibration solutions you will need include a pH 4 and 7 solution for your pH pen and a 1000 PPM solution for your TDS pen.  

It is recommended that you buy calibration solution provided by the manufacturer of your pH and TDS pen. If they do not provide calibration solutions, find suitable calibration solutions at your local PNW.

You are now ready to calibrate!

Calibrating the HM pH Pen

We will start with the HM pH pen. Place the meter into the pH 7 calibration solution. Make sure the probe is fully submerged. If not, add more calibration solution.

Give the pH pen a couple of minutes to settle and provide a reading. The meter should read 7, assuming it is not, we will move onto the next step.

On the HM branded pH pens there is a button that says Temp/Cal. With the probe in the solution, press and hold this button until the letters C-A-L begins to flash on the screen. You will also notice a 4, 7 and 10 icon. Because your probe is in pH 7 solution, the 7 icon should be flashing. If not, use the buttons with the up and down arrow to adjust accordingly. Once you have pressed the ‘enter’ button the screen will continue flashing ‘CAL’ during the calibration process.

Once Calibrated, the screen will flash ‘End’ and your meter will read 7. You have successfully calibrated your pH pen.

You can repeat this process with the pH 4 solution.  Calibrating your pens with two solutions is ideal as it will allow the probe to read quicker and more accurately. You can also repeat this process with the pH 10 calibration solution if you’d like but using only the 7 and 4 solutions is fine.

Calibrating the HM TDS Pen

Now that our pH pen is calibrated, we need to do the same for our TDS pen.

Take the TDS pen out of the cup with water and place it into the 1000 PPM calibration solution. Make sure the probe is fully submerged. Let it sit for a minute.

The next step is to press and hold the Temp/Cal button until the screen starts to flash. Once the screen begins to flash, you can use the buttons with the up and down arrows next to it to adjust the ppm reading accordingly.

Once you have set the correct reading, in this case 1000 PPM, you can press the ‘enter’ button. You have now calibrated your HM TDS pen and it is ready for use!

*Disclaimer – The calibration process explained was done using a HM pH and TDS pen meter. Other brands will have different features and methods of calibration. Please review your manufacturer’s manual for more information

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