Re: Brita filtered water: pH problem

jim schulman wrote:
Once the water is boileed, there cannot be enough HCO3- ions left to
go over 7 pH, even with all dissolved gasses out. This is the problem
with your reading -- if it is correct, it cannot be from carbonates.
Even in icecold water, it's hard to get enough carbonates into water
to get above 8pH

Thanks Jim. I guess a few more measurements are in order, hopefully by
someone with a different setting than mine. I still think that the
imbalance in the carbonate buffering system caused by the ion-exchange
process can lead to enough hydroxyl ion production after CO2 escape to
account for the increased pH, regardless of how many carbonates are
left behind. If the boiled water is left standing in air for a while it
will reabsorb CO2 and get back to more acidic values. Checking some
google results (plenty of aquarium owners or beer brewers seem to get
very scientific about their water) I came across this measurement:
Tap Water: pH 7.8 8 dGH 5 dKH
Brita Water: pH 6.6 6 dGH 3 dKH
Boiled Water: pH 9.0 8 dGH 4 dKH
but it was dismissed by the authors because the water had not cooled
down enough. However, pH measurement at a high temperature has the
opposite effect, it gives a lower pH reading: A neutral water (pH 7 at
20C) will measure around 6 at boiling temp and around 7.4 at 4C.

George (who has a degree in chemistry, but that was so long ago....)

.

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