> From: "Mike Bernardoni" <mikeb at pso_siu.edu>
> Hello, I am getting Lacy Holes in the leaves of some of my Amazon 
> Sword plants.  Could someone tell me what mineral is lacking to cause 
> this problem.

The plant FAQ says:

  ``Is fish food enough to fertilize my plants?''
   Fish food usually provides enough of the three _macro_nutrients,
   nitrogen, phosphate, and potassium (N-P-K), to keep your plants
   healthy. [snip comments about trace nutrients]

We should probably revise the wording of this. I don't believe
that its really good advice any longer.

It may be true for phosphates but current evidence would indicate
that with good lighting and vigorous growth without any other form
of supplementation, that a tank will eventually become deficient in 
nitrogen and potassium over a period of months even if the substrate 
contains soil or an organic fertilizer such as composted manure. 

I hesitate to recommend solid fertilizer in the substrate because 
we have not established how much is appropriate. However, PMDD 
appears to be a safe and reliable method to increase availability 
of N, K and Mg as well as several trace elements. (it's also cheap 
and easy to tune to your requirements) 

Small yellow dots that develop into holes especially in older 
leaves, are a symptom of potassium (K) deficiency.

Sword plants will prosper very well in a very rich substrate
so you can follow the Randall method and "pot 'em up"!!

I would also like to point out that most plants absorb nutrients
much more readily with their roots than through their leaf surfaces 
(despite some comments made recently). I won't go into more detail
at this time but I'm researching materials and hope to have a new
FAQ entry on substrates for y'all sometime soon.

Steve Pushak

Here's some information from Neil Frank which appeared first in
the Jun 25, 95 issue of the APD:

Here is a table I adapted from
 Jacobsen, Niels. AQUARIUM PLANTS (1979). Blandford Press Ltd.

It extends the information recently provided on the digest by 
David Whittaker about mobile and immobile elements.

Other useful information can be obtained from
 Krombholz, Paul.  "Mineral Nutrition of Aquatic Plants, Part 1"

            Leaves to first
Element     show deficiency      Symptom

Nitrogen        Old         Leaves turn yellowish (*)

Phosphorus      Old         Premature leaf fall-off
                            Similar to nitrogen deficiency

Calcium         New         Damage and die off of growing points
                            Yellowish leaf edges

Magnesium       Old         Yellow spots (*)

Potassium       Old         Yellow areas,
                            then withering of leaf edges and tips

Sulfur          New         Similar to nitrogen deficiency

Iron            New         Leaves turn yellow
                            Greenish nerves enclosing yellow leaf tissue
                            First seen in fast growing plants

Manganese       (**)        Dead yellowish tissue between leaf nerves

Copper          (**)        Dead leaf tips and withered edges

Zinc            Old         Yellowish areas between nerves,
                            Starting at leaf tip and edges

Boron           New         Dead shoot tips, new side shoots also die

Molybdenum      Old         Yellow spots between leaf nerves,
                                then brownish areas along edges.
                                Inhibited flowering
(*)  The plants may also become reddish from the presence
     of the red pigment anthocyanin.

(**) Although Jacobsen does not differentiate between new and old leaves,
     David Whittacker reports from a hydoponics book that boron, calcium,
     copper, iron, manganese and sulfur are immobile elements and whose
     deficiencies affect new leaves.