# PH Pen Calibration



## grodude (Jan 7, 2018)

I have a the Oakton EcoTestr Ph2 pen and I haven't used it in years. The calibration is off and I have 4.0 and 7.0 calibration solution. When I put it in the 4.0 solution and hit CAL it reads 7.0. When I put it in the 7.0 solution it reads 10.0. How do I get it to calibrate correctly if it is not reading what it is supposed to. The 4.0 solution reads above 6 and the 7.0 solution reads above 10.


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## Hackerman (Jan 7, 2018)

This one?

http://www.rshydro.co.uk/PDFs/Eutech/ecotestr-pH2-operating-instructions.pdf


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## zem (Jan 7, 2018)

Well if you are sure that your calibration solution is fresh and good, then the meter seems to be far off and will give an error reading when you calibrate it. Try use a soft toothbrush with mild dishsoap, if that doesnt work, contact the manufacturer, but with typical ph probes, it is that you have to keep them wet and if they dry they die and there is a point where they never come back.


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## grodude (Jan 11, 2018)

zem said:


> Well if you are sure that your calibration solution is fresh and good, then the meter seems to be far off and will give an error reading when you calibrate it. Try use a soft toothbrush with mild dishsoap, if that doesnt work, contact the manufacturer, but with typical ph probes, it is that you have to keep them wet and if they dry they die and there is a point where they never come back.



I think I might be at that point. Thanks


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## zem (Jan 13, 2018)

I had a lot of issues with every ph pen that i got, either doesnt work right, or dies very soon. Bluelab ph pocket meter solved my issues 3 years ago and is still operational. I leave it immersed in a fert solution


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## Hushpuppy (Jan 16, 2018)

I also use the Bluelab pens. I get the storage solution which uses potassium salt to stabilize the bulb. I have a glass measuring cup that I keep storage solution in and set the rinsed off pen in that to maintain the calibration. Plus the Bluelab pen that I have prompts me every other month (I believe) to recalibrate it. It is rarely off more than .2 either way when I recalibrate. I don't even use the cap for it because I keep it in the jar of storage solution when its not in use.

The important thing to know is that with any pH pen, you have to keep them in some kind of storage solution (they say not to use distilled water). I like the Bluelab solution but I find that as it evaporates, the potassium salt will precipitate out and build up scale on the sides of the jar. I use clean water to top up that jar of solution and wash the precipitate back into the solution. Every other month, when calibrating, I dump out the storage solution and clean the jar then add new solution and continue on.


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