Low PH

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AirIck

AirIck

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Maybe my apex probe is malfunctioning? I picked up an API test (only PH one test I could find locally in a pinch) and the test came back looking like it was either 7.8 or 8.0 (hard to tell between the 2 colors), however, my apex probe is reading 7.43 AND it was just calibrated again.

could it be possible my probe is getting interfered with by something else causing a reading this low? I’ve heard the salinity probes had issues but I haven’t read any reviews with the PH probe being of concern (this is why I purchased the apexEL.
 

MnFish1

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Maybe my apex probe is malfunctioning? I picked up an API test (only PH one test I could find locally in a pinch) and the test came back looking like it was either 7.8 or 8.0 (hard to tell between the 2 colors), however, my apex probe is reading 7.43 AND it was just calibrated again.

could it be possible my probe is getting interfered with by something else causing a reading this low? I’ve heard the salinity probes had issues but I haven’t read any reviews with the PH probe being of concern (this is why I purchased the apexEL.
Many people would suggest that API tests do not work well (I personally use them). I would recheck the test (the API). BTW, when its between 2 colors (7.8 and 8) - I consider that '7.9'. Also - some recommend periodic replacement of pH probes - every couple years (or so) - yet others have used theirs without replacement for much longer - and seemingly have no problems
 

Randy Holmes-Farley

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Resolution of 0.1 pH with an accuracy of +/-0.02

That must be a typo or a marketing guy wrote it without any understanding of what it means,.

How can the accuracy be better than the resolution? lol Answer: it cannot.

Specifications:

Range:
0.00 - 14.00 pH
Resolution: 0.1 pH
Accuracy: +/- 0.02 pH
Calibration: Manual 2 points
 

arking_mark

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That must be a typo or a marketing guy wrote it without any understanding of what it means,.

How can the accuracy be better than the resolution? lol Answer: it cannot.

Specifications:

Range:
0.00 - 14.00 pH
Resolution: 0.1 pH
Accuracy: +/- 0.02 pH
Calibration: Manual 2 points

True. So probably 0.01 precision.
 
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So I contacted Hanna about the HI98100, and they stated the accuracy is indeed only +/-0.2ph. (I’m guessing its in large part because there’s no built in temp compensation) But since the specs listed on the site said +/-0.05 they are letting me return it. (thanks for @MnFish1 for noticing the lower accuracy listing). Supposedly they have told their marketing people so they can update the website. Just wanted to update the thread for future reference.

I’m going to be replacing it with the following, which has a claimed accuracy of +/-0.005 pH with up to a 5 point calibration.

 

MnFish1

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So I contacted Hanna about the HI98100, and they stated the accuracy is indeed only +/-0.2ph. (I’m guessing its in large part because there’s no built in temp compensation) But since the specs listed on the site said +/-0.05 they are letting me return it. (thanks for @MnFish1 for noticing the lower accuracy listing). Supposedly they have told their marketing people so they can update the website. Just wanted to update the thread for future reference.

I’m going to be replacing it with the following, which has a claimed accuracy of +/-0.005 pH with up to a 5 point calibration.

that might have been @Randy Holmes-Farley
 

Righteous

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Just wanted to update this thread with more information about the Hanna pH testers and accuracy.

I received my new Hanna HALO (HI12302), accuracy +/-0.005, and compared it to my older HI98100 which has a listed accuracy of +/-0.2 (even though it’s resolution is 0.01)

Both measured down to 0.02 difference, so I can confirm that the cheaper HI98100 is pretty accurate.

4E0A3E83-8020-457E-8FBE-E6EBC2DA7351.png


CAD26966-038E-4B9E-9567-9E52BB94E006.jpeg


The new HALO is pretty slick though. It calibrated super easy with the app (I did a 3 point calibration) and it also does it’s own temperature compensation so I didn’t need to float the buffer bags prior to calibration. It also stabilized very quickly compared to the cheaper Hanna.

My guess is that they changed the accuracy listing of the HI98100 either to compete with their more expensive meters, or because without the temperature compensation it’s more prone to user error during the calibration process.

In any case, both agreeing so closely shows my Apex is off by +0.3pH (even after multiple calibration attempts)
 
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