Revised Fertilizer Comparison & Fe speculation

David Whittacker says:

>>Your value for iron in Duplaplant fertilizer tablets of 0.3 ppm does
not agree with the 234 ppm that George posted which brings us back
to my statement that the "apples and oranges" comparison does not fly.<<

Dave, thanks for noticing the typo in my table. There were too many values
of 0.3ppm :-)
I must now modify my arguments.

David also says:
>>How you mix the apples
and oranges matters little. You are still left with a shortfall of certain
essential elements. Keep in mind that George tries to maintain a level of
0.1 ppm iron in his tanks and may use laterite which would add even more
iron to the water.<<

I still think that the mixing of the apples and the oranges (the relative
doses of each) is an important determinant.  It is also important to know
FOR SURE if ALL the iron contained in the tablets, (and the laterite)
actually go into solution. The same is true for the Dupla drops. Both you
and Kevin are assuming that the dose of the tablet is based on a final iron
concentration of 0.1. How did you decide this? I will concede that some of
the trace elements would APPEAR to be in short supply if the later
assumption is true. :-)

I am going out on a limb here (please note that I am not a chemist),  but
suppose that some or all of the iron in the tablets is not chelated and it
is not intended to raise the iron concentration in the water to 0.1ppm.
After all, it is used in conjuction with DAILY drops. If both yield the same
endpoint, then the day for using tablets would cause Fe to be 0.2ppm??
Although the reason is not immediately apparent to me, perhaps the tablet's
iron is intended to deposit into the substrate, say for ultimate conversion
under anerobic conditions. Or, it is intended to react with something else,
like phosphates! For example, iron chloride will cause phosphates to
precipitate as iron phosphate. (this was discussed in TAG V7n1).
Unfortunately, George's more complete analysis does not present chloride
concentrations so we cannot evaluate this hypothesis. After Jim Kelly did
his investigation of laterite, he made me think that phosphate removal may
be one of its potential advantages. The same could be true for other
components of the Dupla approach. I think we need to get Kaspar involved. :-)

For future discussion, here is the corrected table. It would still be nice
to add the relative K, N,  Mg and trace element proportions from the ppdd.

Relative Concentrations of Commercial Aquatic Plant Fertilizers
                                B5 plant     PP Ltd
   Tropica Dupla Dupla Dupla    tissue  DAI  trace
   Master  Daily plant Duplagan culture tab. element
   Grow    drops Tablet cond.   media*       Powder
   (%)     (ppm) (ppm)  (ppm)    (mg)  (ppm) (ppm)
K     .79    -    2490.  10.0     -    17.3     -
P      -    0.7    0.3   1.0      -     7       -
N      -     -      -     -       -    14.4     -
Mg    .39    -    0.3   509.0     -     .15     -
B    .004   2.0   6.7     -     3000    .03    1.3
Cu   .006   0.1   0.2     -       25    .008   0.1
Fe    .07  1180.0 234.    0.3   40000    .19    7
Mn    .04   1.3   36.8    -    10000    .003   2
Mo   .002    -    0.7     -       25     -     0.06
Zn   .002   0.1   0.6    0.3    2000    .01    0.4    
Co      -    -      -     -       25      -      -
ETDA   -     -      -     -      Yes      -     42
HEEDTA yes   -      -     -       -       -      -
DTPA   yes   -      -     -       -       -     13
E123   yes  -      -      -       -       -     -

1.   Dupla Tablet is ppm of element from tablet dissolved in
     unknown amount of distilled water (as per G. Booth)

2.   B5 Tissue culture media is concentration of compounds EDTA
     sodium ferric salt, Na2MoO4.2H2O, H3BO3,MnCl2.4H2O,
     ZnSO4.7H2O, CoCl2.6H2O, CuSO4.5H2O (dosage is 30 ml /30 gal
     of water in 75 gal tank, per Shiao Y. Wang)
3.   Other elemental concentrations known to exist in the above
     fertilizers(such as Ca, S, Cl, Na, Cr, Si, Pb, V, Al, etc.)
     are not shown.

4.   Cobalt (Co) was not included in the analysis of all
     products. Chelators were not included in the analysis of Dupla or DAI

5.   PP Ltd powder is hydroponic trace element mixture previously
     reported by David Whittacker.

Neil Frank                 Aquatic Gardeners Association,  Raleigh NC