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RE: Steve, Roger, Leibniz, et al.....

On the thread discussing the growth of algae vs. vascular plants, and our
attempts to invoke the Leibniz law, Tom Bar waded in with a suggestion from
left field....

"* Or is there more to the chemical bio-cycle momentum idea than
meets the
 eye?Hummm? The plant's may be adding or removing something more subtle than
we think or can observe directly."

I think we may have found a likely contestant for "Who Wants to be a
Millionaire?". Tom may have moved the discussion onto the right path.

I think that we can all agree that the presence of each of the 17 or so
"essential elements" is required in order for plants (either algae or higher
plants) to grow. Our knowledge of and our ability to monitor exactly the
levels of each of those elements that is necessary is limited - this is,
after all, a hobby and not a scientific experiment. Even my anal retentive
self is forced to admit that my LaMotte and Hach test kits might not be
telling me enough of the right things. (But that same anal retentive self
feels more comfort in having spent the money, so I'm happy.)

All life, be it bacterial, plant or animal in nature, exists _within_ its
environment, being affected by the external conditions and also exerting its
own influence on those same external conditions. This is especially true of
plants - they have the ability to produce complex chemical substances from
raw atoms and molecules. Some of those complex chemicals are excreted back
into the external environment in an attempt to modify or control the
external conditions so that they are more conducive to the growth and
reproductive success of the species involved.

Different species of plants can probably produce different "sets" of
chemicals and the effect of those different "sets" of chemicals can produce
a wide variety of observable reactions on neighboring species. For example,
species 'a' might extrude a chemical which has the effect of inhibiting the
growth or reproductive success of species 'b'. Unless species 'b' has a
similar ability to either produce a substance which will overcome the
effects of species 'a's' excretion, or can produce it's own brand of
chemical which has a more efficient and similar effect on species 'a', it is

Additionally, species vary widely in their individual efficiency in
extracting the elements they need for growth and reproduction from the
external environment. That efficiency can change in response to changes in
the external environment - for example more or less light, more or less
water movement, etc. Thus, different conditions can favour one species over

As Diana Walstad noted in her book, "allelopathy may be the 'wild card' in
the formula for controlling algae."

Our aquariums are essentially nutrient rich soups which are very
precariously held in 'balance' by our efforts at husbandry. They are many
orders of magnitude too small and many orders of magnitude too overstocked
(when compared to a 'natural' ecosystem) to be able to attain much in the
way of long term stability without constant outside intervention (i.e.

Our goal is (I think) to tip the scales in the direction which favors the
growth of higher plants (as opposed to algae and photosynthetic
cyanobacteria). Individual tanks have different pivot points - the magic
resides in finding the equilibrium point for your particular tank and then
letting Nature work its wonders. No one path is correct in all situations.

Personally, when I see some algae, I prefer to reach for a magnifying glass
to examine it and wonder in its miniscule perfection rather than reach for
the Chlorox bottle.... but maybe that's just me....

James Purchase