False pH test

tlwilson

LifeTime Supporter
Aug 15, 2010
50
Nebraska
#1
I don't know what I'm doing wrong. Two nights in a row I tested pH and got 7.2. I didn't believe it and immediately tested again using water from the same sample and got 7.6. A third test showed 7.6. I rinsed the tube each time before testing with the sample water. I am careful when I test, (unlike the teenager at the pool store!) How can results be so different from the same bottle of sample water?
 

spidey07

Platinum Supporter
LifeTime Supporter
Jun 1, 2012
266
Louisville, KY
#2
Airation raises ph. In your small sample it could vary greatly with the amount of co2 in the air.

If you testing indoors just squezzing the sample water could cause big variation.
 

duraleigh

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Apr 1, 2007
31,273
Sebring, Florida
#3
What do you think your pH should be? It is pretty rare for pH to have much variance. How old is your reagent?
 

tlwilson

LifeTime Supporter
Aug 15, 2010
50
Nebraska
#4
I'm happy with 7.2 to 7.6, but it is almost never on the lower end unless I add MA and then it goes back up pink in a week. I have a hard time distinguishing the pinks, so I don't know if it is 7.8 or 8.0. My TA is 80 and stays there. I bought a new bottle of regeant 2 months ago. Also, the water bottle I'm using doesn't have a top for squirting it. It's just a capped top. I use 12.5% liquid chlorine and pool life is good. The water is so clear I saw a 1" silver clip on the bottom that blew into the pool.
Additional numbers:
FC 4.5
CC 0
CYA 40

I'm not stressing about the pH, just trying to perfect my technique. Thanks to you kind people on troublefreepool.com, I am in control of my pool. :-D
 

duraleigh

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Apr 1, 2007
31,273
Sebring, Florida
#5
Relax and go swimming. You'll probably get better and better at the pH test but you seem to be keeping it in the 7's which is really all that counts.