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Re: Alkalinity and Phosphates
James Purchase wrote (quoting yours truly):
> "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?
The main factor is that there is only a rather slim chances of getting
phosphate levels high enough to change your alkalinity reading. You would
probably have to be trying.
I've followed up on two or three cases where alkalinity readings appear to
produce erroneous CO2 concentrations and in each case organic acids appears
to be the most likely cause of the problem.
Our aquariums should be organic soup. Plants exhude organic compounds for a
number of different reasons. We daily add organics in the form of fish food,
and plants are forever dropping leaves and roots are dying off. The food and
detritus are highly degradable organics. Driftwood is a very large reservoir
of semi-degradable organic material and soil or peat in the substrate adds
even more. All of the digestible and degradable organics can give rise to
soluble compounds including acids. Many of the additives we use -- e.g.
chelated trace elements, "liquid CO2" and medications -- are organic
compounds and some of those are organic acids.
Given so many opportunities I expect that quite a few aquariums will contain
organic acids that might interfere with the alkalinity titration. If the
concentrations are high enough, then interference will happen.