Copper in acidic Vancouver water?

As I've mentioned to some of you privately, our local Vancouver water
seems to have become highly acidic lately (to the point where it
is no longer safe for adding in large amounts to a fish tank) Recently
I've also noticed the melting of my new Ludwigia repens leaves that
I had been so happy they were growing. Since Karen mentioned that
Ludwigias were susceptible to copper poisoning and the symptoms matched,
this led me to wonder if I have been suffering from copper poisoning
for some time from our usually acidic Vancouver water which is now
really acidic. What the heck are they putting in our water to make
it so acidic? From the tap it's below pH 6 but a CO2 measurement
using the LaMotte kit only indicates 5ppm of CO2. To me this would
indicate the presence of another acid. Any suggestions? If there
is Copper in the water, how could I safely remove it (ie. pretreat
the water) without leaving compounds that might also precipitate
my Fe(EDTA)? From Karen's comments, it doesn't sound as if she has
found a highly successful method.


On the subject of Humic acid:

I'm investigating an issue with humic acid which -might- indicate
that more than a small amount could have allelopathic properties. You
probably shouldn't add any to your tank or substrate on speculation 
that it might have wonderous properties just yet. Any of you
aquatic botanists care to comment? (either here or offline?)