Re: Aquatic Plants Digest V2 #121

>From: Stephen Pushak wrote Wed., June 5:

>Subject: 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.

It sounds like the city is not adding lime to the water.  If the water was
more alkaline earlier, either they were adding lime then, or they were
getting the water from a different source, probably a well.  Soft, acid
water usually comes from a reservoir in granite country, where there is no
limestone.  It can get a pH around 5.5 just from the small amount of CO2
absorbed from the air.  Air pollution can lower the pH down to around 3.0
(acid rain).  I think your LaMotte test kit will count all acids as
carbonic acid.  I am pretty sure that it just titrates acidity to the
phenolphthalein end point of pH 8.1.   When I was in graduate school at
Tufts, which is in the Boston area near where Karen Randall lives, I had
the same problems with copper that she has.  I found that I could let a
tank of tap water age for a month, and it would still kill a snail in 30
minutes and a fish in 4 days.  People in Boston who had any success at all
with fish always used activated carbon filters.  By the way, snails are
very sensitive to copper, and can be used to test the water to see if it is
OK.  However, when the copper is high enough to kill snails, the water will
still support some life.  I saw the ciliate, Vorticella, growing in aged
Boston tap water that killed snails.

My final solution was to borrow some 5 gallon plastic containers from a
friend and go to one of the local reservoirs in the area and collect the
water from the outflow.  (The reservoir, itself, was fenced in.)  I
filtered the water through sand to trap any hair algae filaments and kept
it in several empty aquariums.  It was very healthy water and all my plants
snails, etc. did fine.  One of the professors at Tufts tested the tap water
for copper and got a level of 5 ppm.  When I heard that, I started drinking
my collected water.  It is probably my imagination, but I thought that I
was healthier after I stopped drinking the tap water.

>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?)
I wouldn't worry about allelopathic properties of humic acids unless you
actually uncover evidence that these properties exist.  Usually the worry
about humic acids is that they absorb light that you want your plants to
get.  I have one tank that has a lot of humic acid from soil that had a lot
of dead leaves composted in it, and Ceratopteris grows very well there,
floating, but some plants deeper down are not getting enough light to grow.

Paul Krombholz                  Tougaloo College, Tougaloo, MS  39174
In cool, pleasant, Mississippi where it is cool if the high temp is below
90 and dry if the dew point is below 70.