PH result changes after 5mins

[xxamyxx85]

I’m a little confused, i use the api master test kit and I always read my test for ph the moment I do it, it is usually 7.6, today i tested my water change water because I use the pozzani nitrate removal filter. I did the test and it was the usual 7.6 but I left the test tube on the side and after 5- 10 mins the reading changed to around 6.6, can someone please tell me which result is right?

 

[Essjay]

With pH, it's the colour as soon as you've added the reagent and shaken the tube. Ignore the colour after it stood for 10 minutes.

 

[xxamyxx85]

With pH, it's the colour as soon as you've added the reagent and shaken the tube. Ignore the colour after it stood for 10 minutes.

I was hoping you was going to say that. Thank you.

 

[Colin_T]

It probably changed due to carbon dioxide in the air or dirt in the test container.

As essjay said, just use the result from when the test is first done and disregard results that occur in the test phial more than a couple of minutes later.