Re: Alkalinity and Phosphates

["roger" <roger at spinn_net>]

Scott wrote:

> I wondered, if the organincs cause a false high KH reading
> and a false high pH reading, then the errors might tend to
> cancel out in terms of of the pH/KH/CO2 table?  Doesn't
> seem likely since the effects can vary for the two tests,
> not to mention from one organic to another.

Scott:

I'm sorry if I gave you the impression that organics would
interfere with the pH test.  As far as I know they don't.
The presence of organics may cause the pH to change, but
that isn't a false effect.  That's a real change and it
doesn't hurt the test results.

Problems come up with the alkalinity (KH) test because the
method assumes that all of the alkalinity is bicarbonate.
When that isn't true -- as when there are organic acids 
measured as part of the test -- then the assumption is
wrong and the test results are bad.

Similarly, problems arise with the acidity (CO2) test
because the method assumes that all of the acidity is CO2.
When that isn't true -- as when there are organic acids
contributing to the acidity -- then the assumption is 
wrong and the test results are bad.


Roger Miller