PH Meter and TF-100 Discrepancy

Enkil810

Member
Aug 16, 2014
15
Winnie/Texas
Just thought I would get the forums opinion. I ordered the PH meter with my TF-100 kit. I calibrated it per instructions. The meter reads my pool water at 6.9 and my TF100 says more like 8.0. I also checked it with my ColorQ pro which I use for a back up. It says 8.0 Why would the meter read correct in the buffer solution but be completely off in the pool water? Any ideas?
 

GrandizerGo

Active member
Jun 21, 2019
39
Ontario, Canada
Have you tried leaving the meter in for a while and swish it around a bit? I have one meter that reads a little high initially and then settles down. My second meter is always really high initially until I leave it for a couple of mins.
 

gregsfc

Bronze Supporter
May 27, 2014
204
Cookeville,TN
Just to make sure...You're not testing with high fc levels are you? Below 7 gives me accurate results with the Taylor kit included in the TF-100; otherwise, If my fc is high, it'll always show 8. I had a Chlorox brand oto/ph tester and it was even more sensitive to high fc levels. Always showed 8.0 if fc was above 4.
 

ajw22

Gold Supporter
TFP Guide
Jul 21, 2013
20,394
Northern NJ
Cheap pH meters are pretty much junk and get unreliable quickly. They may work for a bit but don’t last long. Their calibration may vary with their battery strength.
 
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Reactions: TishTash

scottts

Gold Supporter
Nov 13, 2019
161
Gilbert, AZ
I should probably give the SpeedStir backlight another try with the FAS/DPD test. After X number of drops, I would think it’s clear, but then immediately after shutting off the light, I noticed it was still pink (as opposed to turning pink over time). Retesting without the light (either on the SpeedStir or manually swirling) confirmed the extra drop. So too bright a light can mask a remaining pink tinge.
I've noticed this as well and I've learned that if you view the sample from the side rather than top-down, you can see the pink better. Once its clear from the side then I don't see any pink after shutting off the light. FWIW.
 

TishTash

Bronze Supporter
Aug 8, 2018
155
Merrick, NY
I've noticed this as well and I've learned that if you view the sample from the side rather than top-down, you can see the pink better. Once its clear from the side then I don't see any pink after shutting off the light. FWIW.
(the post to which this responds should actually (and was moved) to here: :))