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Re: Alkalinity and Phosphates



Roger & Scott:

Duhhhhhh! I missed that post and the article entirely (I am a member of the
AGA and I have the copy of TAG you mentioned). Thanks to you both for
pointing it out. I guess that I'm a bit behind on my reading....

Roger wrote:
"James, you and Cavan should both know that there is almost no question that
can be answered that hasn't already been answered on APD."

Really? So all the issues and problems have already been solved? Hmmm, wish
someone had told me that a while ago...... ;-)

"Sulphates do *not* contribute to alkalinity.  I'm not sure about borate.
If you have borate concentrations high enough to read as part of your
alkalinity then you have other problems to worry about.  Boron is toxic to
plants at fairly low concentrations."

If think that I made a typo in my original question, "sulphates" should have
been "sulphides". From the City of Boulder/USGS Water Quality Monitoring web
site (http://bcn.boulder.co.us/basin/data/NUTRIENTS/info/Alk.html), I found
the following:

"Alkalinity is a measure of the buffering capacity of water, or the capacity
of bases to neutralize acids. Measuring alkalinity is important in
determining a stream's ability to neutralize acidic pollution from rainfall
or wastewater. Alkalinity does not refer to pH, but instead refers to the
ability of water to resist change in pH. The presence of buffering materials
help neutralize acids as they are added to the water. These buffering
materials are primarily the bases bicarbonate (HCO3-), and carbonate
(CO32-), and occasionally hydroxide (OH-), borates, silicates, phosphates,
ammonium, sulfides, and organic ligands."

I understand that the presence of a lot of these ion species would indicate
very polluted water and are not something that the average aquarist needs to
worry about, but it is nice to be able to actually confirm that fact in a
way that doesn't depend on just taking someone's word for it. Some of the
dosing recommendations and chemicals proposed both here on the APD and in
other online forums just seem (to me) to be slightly suspect (or at least
highly unusual) and I feared that some folks might be creating chemical
soups that defy the bounds of "normal". Being able to figure out what these
things do to water parameters can help relieve my fears.

In your referenced post, you commented:

"The chances of getting interference from organic acids appears to be far
higher than the chance of a problem arising from phosphate concentrations."

Care to elaborate on that statement?

Thanks,

James Purchase
Toronto