Ph Testing question ???

[Bruce in Sb]

So everything has been going great with the swim spa so far. However, the last 3 times I have tested Ph using a Taylor K-2006 test kit, the ph has read low, like 7.2 but if I re-test it right away with the same water sample it shows 7.6.
The first time I figured I had the wrong number of drops ... the second time I was suspicious ... but just now it has done it a third time.
Could the reagent be going bad? It was a brand new kit last September.

Any suggestions would be great!
Thanks,
Bruce in Sb

 

[woodyp]

If the kit has been kept indoors and cool, the chems should be just fine. Look at it up against a white background.

 

[Bruce in Sb]

It has been stored indoors so I'm sure it's OK. The color change goes from Yellow to Pink with the same water sample and number of drops. I use the same white background every time so something new is happening..
Thanks ...

 

[Bruce in Sb]

Any other ideas as to why this is happening?

 

[jblizzle]

Something contaminating the vial that gets washed out in the first test?

Buy another bottle, only a few bucks. See if that helps.

 

[JamesW]

Are you rinsing the tube and cap before and after each test?

 

[Bruce in Sb]

Good idea... I'll try a new collection bottle and rinse the tester tube better tomorrow...
Thanks for the suggestions!

Something contaminating the vial that gets washed out in the first test?

Buy another bottle, only a few bucks. See if that helps.

 

[JamesW]

Sometimes people use their hand to cap the tube. If they have anything on their hand, it could contaminate the sample.

 

[jblizzle]

I meant another bottle of reagent ... not a collection bottle.