Electronic pH tester unstable

Enumjon

Active member
Apr 30, 2020
43
Tijeras, NM
Hi all. I purchased the electronic pH tester at the same time I got the TH-100 test kit. The pH tester keeps losing the calibration, and needs to be recalibrated weekly. Each week it will be at least 1.0 off, either high or low. Is this normal? I use the tester daily, rinse it with distilled water after each use as instructed, and keep it stored inside the house - so dry, warm, and out of sunlight.
 

Enumjon

Active member
Apr 30, 2020
43
Tijeras, NM
I thought that a big reason for getting these was ease of use. Having to recalibrate weekly - and only trusting the readings the day I calibrate - makes it less than helpful.
 

duraleigh

Admin
Mod Squad
TFP Expert
Platinum Supporter
LifeTime Supporter
In The Industry
Apr 1, 2007
34,056
Sebring, Florida
Here is the opening paragraph in the description..... It seems to me like it is reasonably plain that you need to calibrate the meter. Every week (really?) seems excessive so I would say to contact them.
This pH meter is the perfect device for testing the acidity or alkalinity of liquids. It comes with a small screwdriver for calibration. It is easy to use - simply remove the protective cap and immerse the electrode in the solution to be measured. Included with the meter are 6.86 and 4.01 pH buffers for an calibration. Instructions for calibration are also included with the pH meter.
One year warranty
 

mgtfp

Bronze Supporter
Mar 5, 2020
280
Melbourne, Australia
I am quite happy with my pH meter, I am not good with colours. I frequently verify the calibration with a buffer solution, but I don't often have to recalibrate, reading remains stable for weeks.

What is more critical in my case is to be very thorough about contamination. E.g. after verifying the calibration with a buffer solution, I first rinse with distilled water, shake it off and dry with a tissue. Then I rinse and shake off multiple times with the pool water to be tested before doing the actual test. And then I make sure to wait long enough for the reading to stabilise.

My tester also works much better when stored in storage solution. But that influences more the time it takes to stabilise the reading, rather than the accuracy.

If you don't store in storage solution, then you should add at a drop of tap water to the container around the electrode to keep it hydrated. Never store in distilled water, that basically pulls ions out of the test head, that can destroy it. If it just dries out, it needs to get reactivated with storage solution (in my case 3 molar KCl).
 

mgtfp

Bronze Supporter
Mar 5, 2020
280
Melbourne, Australia
I have an Apera pH60, cost me about 180 AUD, in the US you get it for just above 100 USD. I tried it because I am hopeless will the colour test. I see it turning yellow at 7.2, but everything between 7.4 and 7.8 looks the same to me. Very happy with it.