Ph raise in aged water?

[2075turner]

Why does my ph raise slightly when I age tap/ro water. When I take the reading from the tap it reads 7.0, after 24 hrs it reads 7.5? The mix that I am using is 1/3 tap, 2/3 ro. Thanks, Evelyn:)

[seanyuki]

Hi Evelyn,

Are you using Ph pen monitor or ph test strips?

Cheers
Francis:)

[2075turner]

Hey Francis,

I have a Hanna Instruments Pen type.

:)Evelyn

[Don Trinko]

Gasses disoved in the tap water escape. This typicaly raises the ph. My tap is 7.4, after 24 hours it is typicaly 7.8.. Don T.

[Graham]

The main dissolved gas is CO2....which forms carbonic acid when in water which lower the pH
Mine comes out at 6.1 or so and goes to 7.5>7.8

[2075turner]

Thanks Don and Graham,

I thought that it was something to do with the water chemistry changing as it sits, I wasn't worried about it, just wanted to know what was happening.

Evelyn:)