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Dupla Fertilizer Contents


  1. [F][plant] CARBON as a SUBSTRATE
    by (George Booth) (8 Aug 1994)
  2. Dupla fertilizer
    by (George Booth) (27 Apr 1995)
  3. Dupla Fe, K Test
    by "Christopher Coleman" <christopher.coleman/> (Fri, 4 Dec 1998)

[F][plant] CARBON as a SUBSTRATE

by (George Booth)
Date: 8 Aug 1994
Newsgroup: rec.aquaria

Len Trigg ( wrote:
> Reading the little instruction sheets that come with the Duplaplant 24
> daily drops and the Duplaplant waterchangely tablets, it seems that the
> iron is actually in the tablets, not the daily drops (prove me wrong). 
*That* I can do :-). 

The following tables show the components of the Dupla water conditioners
and fertilizers.  All quantities are in parts per million (ppm or mg/l) of
the raw product and do NOT represent the actual dosage when diluted
according to the directions.  This data only shows the relative proportion
of elements in each product and does not represent the proportions between

Duplagan water conditioner

Used at each water change to add organic acids beneficial to slime coat
production and to add some trace elements that have long term stability.
Note that the inorganic acids are "natural" versus artificial polymers used
in Novaqua type products (according to the local fish store).

Ca  31.0 ppm    Mg 509.0 ppm    Na  54.0 ppm    K   10.0 ppm    P    1.0 ppm
Al   0.5 ppm    Fe   0.3 ppm    Mn  <0.1 ppm    Ti   0.1 ppm    Cu  <0.1 ppm
Zn   0.3 ppm    Ni   0.1 ppm    Mo  <0.1 ppm    Cd  <0.1 ppm    Si   2.0 ppm
Cr  <0.1 ppm    Sr   0.3 ppm    B   <0.1 ppm    Pb   0.3 ppm    V   <0.1 ppm

Duplaplant fertilizer tablets

Used at each water change to add trace elements that have long term
stability.  Note: for the analysis, a tablet was dissolved in distilled

Ca   5.5 ppm    Mg   0.3 ppm    Na 116.0 ppm   K  2490.0 ppm    P    0.3 ppm
Al   0.4 ppm    Fe 234.0 ppm    Mn  36.8 ppm    Ti   0.6 ppm    Cu   0.2 ppm
Zn   0.6 ppm    Ni   3.7 ppm    Mo   0.7 ppm    Cd  <0.1 ppm    Si   5.7 ppm
Cr   0.1 ppm    Sr  <0.1 ppm    B    6.7 ppm    Pb   0.1 ppm    V   <0.1 ppm

Duplaplant 24 daily drops fertilizer

Used daily to add trace elements that are either are unstable or are toxic 
in large doses.

Ca   1.5 ppm    Mg  <0.1 ppm    Na 484.0 ppm    K   <0.1 ppm    P    0.7 ppm
Al   0.5 ppm   Fe 1180.0 ppm    Mn   1.3 ppm    Ti  <0.1 ppm    Cu   0.1 ppm
Zn   0.1 ppm    Ni   0.2 ppm    Mo  <0.1 ppm    Cd  <0.1 ppm    Si   0.8 ppm
Cr   0.2 ppm    Sr  <0.1 ppm    B    2.0 ppm    Pb   0.5 ppm    V    0.2 ppm

The metal assay was done by the Soil Testing Laboratory at Colorado 
State University using an "Inductively Coupled Plasma Atomic Emission 
Spectrometry" technique.  It basically takes a sample and adds enough
heat to get any metals to an their atomic composition and runs a spectrum
on them (this description may be a little hazy - my wife is the chemist
in the family; I'm just an EE).  The instrument is very reliable and is
accurate to the pico-molar range (I rounded the numbers to the nearest
0.1 ppm).  It only does metals, so we had no data on Nitrogen.  As far
as we know, there are no nitrates or phosphates in the Dupla products.
This is via LaMott (nitrate) and Dupla (phosphate) test kits at home. 

George Booth                         "The power of accurate observation is              commonly called cynicism by those who 
Freshwater Plant Tank Technology      have not got it" - George Bernard Shaw.

Dupla fertilizer

by (George Booth)
Date: 27 Apr 1995
Newsgroup: sci.aquaria

David Brockman Wheeler (dwheeler-at-leland.Stanford.EDU) wrote:
> In article <>,
> Richard J. Sexton <> wrote:

> >Now, what about these [Dupla] plant fertilizer tablets. They give
> >a dosage, but *not* a frequency. Once a day ? Once a week ?
> >Once a year ?

> Dose entire tank at set up (or whenever you begin ferilizing...although, in 
> thos case i might not do it all at once) and then dose change water.

Let me clarify that.  First of all, there are two sizes of Duplaplant 
tablets, one that treats "20 liters" of water and one that treats "50
liters" of water.  Use the info on the container to figure out which 
ones you have, i.e., if the container has 100 tablets and it treats 
5000 liters, you have the "50 liter" tablets.  

When you first set the tank up or first start using the tablets, add enough
tablets to treat the entire volume of the water.  Hint: figure out how 
much water you *actually* have, as in, a "55 gallon" tank probably has
43 gallons of water when you take into account real measurements and
the displacement of gravel, rocks, driftwood, etc.  The tank vendors 
are a bit optimistic in their volume calculations. 

When you change water, add enough tablets to treat the amount of new water 
you added.  Hint: try to change an amount of water that matches the 
size of the tablets you have (20L, 40L, 50L, 100L, etc).  It is 
recommended that about 25% of the  water is changed every two weeks. 

In real life practice, we use a little less than the recommended dosage
of tablets and adjust the drops according to the tank's requirements. 
We change 150L of water and use tablets for 100L.  We start drops 3
days after the water change and dose the following daily: 

  85 g tank    2-3 drops
  90g tank     3 drops
 100g tank     4 drops
 120g tank     5 drops

We try to maintain iron levels at 0.1 ppm as determined by a Lamotte iron
test kit.  If we are adding too much, thread algae (long stringy stuff
not mechanically attached) will begin to develop.  

If you are adding the Dupla fertilizers, be sure to have good light and 
extra CO2 or the fertilizers will just increase your algae production. 

George Booth                         "Nothing in the world is more dangerous             than sincere ignorance and conscientious 
Freshwater Plant Tank Technology     stupidity" - Martin Luther King, Jr. 

Dupla Fe, K Test

by "Christopher Coleman" <christopher.coleman/>
Date: Fri, 4 Dec 1998

I recently submitted the Duplaplant and Duplaplant 24 fertilizers
from the Dupla fertilizer system for testing to the University of Maine
at Orono's analytical lab which is maintained by their department of
Plant, Soil, and Environmental Sciences.

The results were as follows:
Fe: 13.2 mg/L
K: 140.0 mg/L

Fe: 0.455 mg/L
K: 0.042 mg/L

Testing details
All tests with exception of the Duplaplant24 were performed
using a Plasma AtomComp inductively coupled plasma emission
spectrometer. K testing for Duplaplant24 was performed using a
Thermo Jarrell Ash atomic absorption spectrometer due to its low

Sampling details
2 tablets from two separate lots were diluted in 1L of distilled
water; the solution was than diluted with 1L more of distilled
water to obtain a 1 tablet concentration equivalent.

10 "typical" sized drops were diluted in 1L of distilled water; the
solution was submitted as is for testing and the numbers presented
here adjusted by a factor of 10 to obtain a 1 drop concentration

The recommended rate of dosing into aquaria is 1 Duplaplant tablet per
20L of water change water and 1 Duplaplant24 drop daily per 50L of total
tank water. At those rates, the products would produce iron concentrations
in the tank of 0.66mg/L for Duplaplant tablets and 0.0091 for Duplaplant24
drops. The Duplaplant value seems high and inconsistent with Lamotte test

I note that an earlier post in the Krib also performed Fe and K
testing on Duplaplant tablets. While the sampling than was done
using an unreported amount of distilled water, the proportion of
iron to potassium then (Fe=234 mg/L, K=2480 mg/L ) and now
is highly consistent. This leads to speculation on the value of
the remaining parameters measured in the earlier test to obtain values
when diluted in 1L of water.

Finally, before submission, the Duplaplant24 sample was also
tested for iron using Lamotte test kit model P-62. ( 0.2 accuracy in the
range of 0.05 - 1.0 ) The results were 0.11 mg/L or a deviation
from the spectrometer's results by a factor of more than two (2).
Is this is acceptable at the very low concentrations involved?

Christopher Coleman

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