Mash ph measurement problem?

[BigdogMark]

This past Saturday my brewbud and I cooked up the Centennial Blonde It was one of our smoother AG efforts, and the preliminary results look promising. One of the things we did this time was take out about a tablespoon from the mash after 5 minutes to measure the ph. We let it cool to 78 degrees then I tested with the ph strips we got from the LHBS. We had two tubes of strips, one tube read less that 4.6 on five tests, the other tube read 5.0 on five tests. Our water is quite hard and we diluted it by 60% and added a few salts and 5.2 buffer. I was expecting the ph to be on the high side due to the alkalinity, even after dilution. Are the test strips just useless? We got good wort and the fermentation is going as expected.

 

[BigdogMark]

I was hoping for some responses regarding the reliability of the ph test strips or some flaw in my testing. Does anyone else do ph testing of the mash, and if so, what are you using? And if you are willing to share, where did you buy it?

 

[conpewter]

I've not dealt with them a lot but I know there is a .3 PH error on the colorphast strips according to some testing, I need to find the results they posted.