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TMG - Potassium

Karen Randall wrote:

> The interesting thing is that even though I believe
> Dupla is lower in K than Mastergrow, there must have
> been something else lower in the Dupla product that
> limited my growth, because now, even with the Mastergrow,
> I need to add K from time to time

Based on their label and dosing instructions, TMG will maintain
a dosed / tank concentration of  0.79mg/L of K.

The independent analysis I had done recently of Duplaplant indicated
the potassium level on a dosed / tank basis of 7mg/L.  There is
something more interesting I learned in this: I also tested the products
( Duplaplant and Duplaplant24 ) and the numbers I obtained for
both the iron and potassium were not the same as George Booths
prevous post of his (similarly obtained) lab results,  but the numbers
were in almosts exact proportion: his solution of Duplaplant contained
17.79 times as much potassium as mine and 17.73 times as much iron
suggesting his solution was diluted about 17 times less than mine. The
numbers  I present were diluted in 1L of distilled water. George has
indicated that at the time he was not certain of the dilution of his
solution which he tested so his numbers provide a good understanding of
the relative proportion of the different chemicals tested for in the
tablets.  I posted this recently.  I'll include it below.

=============== original post ===============
To: "ActWin / APD" <Aquatic-Plants at actwin_com>
Subject: Dupla Fe, K Test
From: "Christopher Coleman" <christopher.coleman at worldnet_att.net>
Date: Fri, 4 Dec 1998 11:59:06 -0500
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 results.

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
extrapolating 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
christopher.coleman at worldnet_att.net

=============== end original post ===============