pH meter and the mysteries of pH

BowserB

Silver Supporter
Jul 29, 2018
657
"Old" Katy, TX
Pool Size
15000
Surface
Plaster
Chlorine
Salt Water Generator
SWG Type
Pentair Intellichlor IC-40
I have the meter from TFTestkits.com, along with all the other stuff they sell. I have trouble with color matching, and since I generally have my FC at 6, the drop tests rarely get used. Over time, I've bought various calibration powders to mix and calibrate the meter, but recently in the process of discussing non-pool pH matters, I did some non pool pH testing and research with fairly unexpected results. This investigation started with a conversation about two recent pop-health fads: apple cider vinegar and baking soda, and a friend who mixes them with water as a daily potion. What, you ask? Yeah, me too.

Anyway, pure water has a pH of 7, as does distilled water immediately after distillation. However, distilled water absorbs CO2 from the air, and its pH drops, possibly even before it's bottled. Otherwise, why wouldn't you just use distilled water by itself to calibrate a pH meter? Maybe a sealed bottle of medical-grade distilled water (is there such a thing?) would come close to 7. ACV has a pH of around 2.75. Baking soda is 8.3. My potassium-softened tap water is 7.7, and my reverse osmosis drinking water comes in at 6.7. Water from a half bottle of distilled water that has been open for several months, says 6.0! And these domestic water tests I've reported here is from the TFTTestkits meter, but now I have doubts about the meter, since I've relied on calibration powders mixed with "distilled water" to calibrate. Clearly I need to go back to calibration liquids like sold by TFTTestkits.com, since who knows what the pH really is with powders added to mystery water pH.

Bottom line is I don't really know the pH of my pool water, do I?
 

ajw22

Gold Supporter
TFP Guide
Jul 21, 2013
29,906
Northern NJ
Pool Size
35000
Surface
Plaster
Chlorine
Salt Water Generator
SWG Type
Pentair Intellichlor IC-60
Bottom line is I don't really know the pH of my pool water, do I?

GIGO.

Do a drop pH drop test. Anywhere in the 7's is ok.

I have only used calibrating solutions with the pH meters I have used. I found the yellow pH meter TFT sells to get more inaccurate and lose calibration over time. I have gone to more expensive pH meters that seem to be more reliable.
 
Thread Status
Hello , This is an inactive thread. Any new postings here are unlikely to be seen or responded to by other members. You will get much more visibility by Starting A New Thread