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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. Plant condition might be a option but I have never
observed an overt element deficiency in my plants. Just slow growth in
some species, rising nitrate levels, and outbreaks of algae. Is there
another trace element I can measure effectively to determine PMDD dose
size. Ideally it would be something used by the plants readily and
quickly maybe sulphur (.05% to 1.5% concentration in dry weight if
plant) or manganese (.0005% to .15% concentration in dry weight of
plants). How quickly is sulphur and manganese used in plants, and can
they be measured effectively.
Any input anyone can give would be greatly appreciated.
Thank You,
--Grover
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