pH 8.8 (off the scale)
KH 3 dKH
GH 7 dKH

So, basically (no pun intended), this water is horrible.

Why is that horrible?

The pH of tapwater should be measured after the water is aerated for 20
minutes, or allowed to sit in a cup overnight. The water in the pipes may have
extra CO2, or be CO2-deficient. (The water company sometimes adjusts the pH of
the water that way, in order to prevent pipe corrosion.)

The surprise
was what i measured in my aquarium:

pH 6.6
KH 2 dKH
GH 7 dKH

Sounds normal, if you are injecting CO2. The KH probably dropped a little due
to the nitrogen cycle in the tank. It gradually eats up the KH in the tank.
(One reason why regular water changes are important.)

Problem is that
i have more than enough general hardness for plants as it is, and
don't want to take the typical approach to raising alkalinity by
throwing in some shells and such (Calcium Carbonate - CaCO3), because
that will also raise the GH.

Don't worry about it. Plants like hard water. I add calcium carbonate
regularly to one of my planted tanks. (It's heavily stocked, so it's hard to
keep the pH up, even with large weekly water changes.) The fish don't mind the
low pH, but the snails do.


Leigh

http://www.fortunecity.com/lavender/halloween/881/