"Bill Stock" wrote in message
...
My tap water has always had a PH around 7.5. But lately my tanks have been
running over 8, where they used to be around 7.6 - 7.8 in the past. So I
tested the KH (5) and PH (7.0) of my tap water, which would seem to
indicate 15 ppm of CO2. I'm a little surprised to find it this high during
the summer (warmer water). I'm letting a batch of tap water sit, so I can
test the PH after the CO2 escapes.

I don't know what the KH was in the past, the city water documents no
longer list KH or DH.



Thanks for the information. Tap water tests 0 for Phosphate, but I was
adding it to the tank for the floating plants. So that might explain the PH
readings in the tank.

I tested the PH of the tap water that I let sit for 24 hours and it's still
about 7. So now I'm really confused. Can the KH change with the outgassing
of CO2?