Re:Macro Nutrient Deficiency

Michael Irlbeck writes....

>Anybody know of specific symptoms or signs to look for when suspecting macro
>nutrient deficiency?

The aquarium literature is short of information along these lines.
"Water Plants in the Aquarium" by Ines Scheurmann talks about the
symptoms of CO2, nitrate, and phosphate excess, as well as CO2,
iron, manganese and potassium deficiencies.

Hydroponic Food Production by Howard Resh contains a few pages
devoted to the visible signs of deficiencies and toxic levels
in both macro and micronutrients. He includes a procedure for
narrowing the search for the element out of balance. I think
some of it would apply to aquatic plants and when a problem
arises in a tank, I look for the symptoms he mentions in his
book, not always with success. What little I know, I gleaned 
from his book and it comes recommended.

A surplus of one element, say manganese, could cause a deficit
of iron. Chlorosis caused by a shortage of sulfur turns the
leaf pale green; a shortage of iron, yellow. He points out that
it is extremely difficult to determine a problem without lab
testing, and that deficiencies of two or more elements can
result in visible signs quite different from those produced
by a lack of either element singly. Also each species of plant
reacts in a slightly different fashion. I don't know how much
of this applies to us.

Previously I mentioned the division between mobile and immobile
elements. Apparently it is not an either/or proposition, as there
is some gradation. It is a good starting point.