Water quality message.

I have been reading this list for several weeks and find it
a great source of information.  I'd like to thank everyone
who contributes to it!

I've setup a planted, 48 gallon tank two months ago and have
let it cycle.  When I set up the tank I put in 8 black neon
tetras who seem to have done very well through the cycling.
I also  put in about 12 potted plants from 6 species
(names unknown).

When I first got the tank I tested the local water (I'm in
Vancouver, BC) and found the following:
pH = 6.0
Hardness (ca, mg) = 0-10ppm (very soft)

After discussing this with the aquarium store they said that
I should raise my pH.  They gave me a 2 (1 lb.?) bags of
dolomite (sp.?) and told me to add this to the gravel when I
set up the  tank  They said nothing about the hardness.

After setting up the tank and adding the fish and plants, I
tested the water to be 7.4 pH.  This is way higher than my
target pH (6.6-6.8).  Furthermore, when I do a partial water
change  with 6.0 pH tap water, the tank shoots back up the
7.4 in a few hours.  When I talked to another guy at the 
store about it, he said I put in too much dolomite in the
tank and  recommended that I replace the gravel in the tank
(!) and put 1/4 bag of dolomite per week until the pH levels
off at the pH I want.  He recommended a pH of 6.6 for the
fish I was  planning to get and to keep the plants healthy
(CO2, etc.).

After reading the Aquaria FAQ and the discussions on this
list I have the following questions/concerns.

1) Is the dolomite solution recommended to me going to work?
With such a low hardness, isn't my pH going to be too
susceptible to fluctuations?  With the dolomite in the
gravel I won't  have any way of regulating it's affect.
What are my other options for achieving a stable pH of

2) Do I need to add buffer or increase the hardness of my

3) Is leaving my tank water at pH6.0, and very soft a
viable solution?  Or maybe even leaving it at 7.4 with the
dolomite buffer?  Won't the plants be starved for CO2 at a
pH of 7.4?

4) I've heard that a CO2 injector can be used to regulate pH.
Is this a viable option?  If so what make/model should I look

Thanks in advance for anyone who can help.

Christian Cotichini.
Vancouver, BC