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RE: Aquatic Plants Digest V3 #820



> From: "Michael Bartnik" <rev_grover at hotmail_com>
> Subject: Questions about PMDD
>
> I have a few questions about PMDD that I hope someone could answer.  Let
> me start out by stating that I won't argue about whether PMDD method
> works.  It clearly does.  I am having trouble determining proper dosing.
> If I understand correctly the best method is to measure the iron content
> of the water and dose enough PMDD to keep iron levels at .1 ppm.  I'm
> using terralit as a substrate additive and have never had insufficient
> iron level in my tank <.1 ppm (also no signs of iron deficiency in my
> plants).  In addition recent posts have been pointing out that the test
> kits used are not measuring chelated iron.  The forms of iron
> registering on the tests are not the ones being used by plants.
>     This leads me to think that I should be using another method to
> determine dose size.

People keep saying that, but I know that my LaMotte kit shows iron when I
add my PMDD-clone trace element mix, and then it shows the level dropping as
the plants use it up, and when it shows zero I better add some more or the
plants start to suffer.

I'm not a chemist and do not understand why chelated iron should or should
not register or why it in fact does for me, I only know that here, it works.

Frank.
-----
The very act of seeking sets something in motion to meet us;
something in the universe, or in the unconscious responds as if
to an invitation.  - Jean Shinoda Bolen

http://home.istar.ca/~fir