Re: Balance and lighting
To: Aquatic-Plants at actwin_com
Subject: Re: Balance and lighting
From: Charley Bay <charleyb at hpgrla_gr.hp.com>
Date: Fri, 13 Oct 95 10:51:46 MDT
In-Reply-To: <199510130739.DAA21184 at looney_actwin.com>; from "Aquatic-Plants-Owner at actwin_com" at Oct 13, 95 3:39 am
Mailer: Elm [revision: 70.85]
Thanks to several very recent posts, I have an opportunity to
illustrate through example what I just said about "state change",
"steady-state", and system dynamics. I'm going to leave
all these quotes anonymous, in case anyone feels I am
"nit-picking" terminology. This is ONLY an example of an
"alternative" way to describe things.
Again, the premise:
"Balance" or "optimum" is arbitrary, un-definable, and
un-measurable. The terms are thus irrelevant.
"Steady-state" is an accepted biological term used by natural
resource managers in the real world reflecting the eventual
stabilization of systems. I am re-defining this term for the
aquarium hobby for the purposes of describing, measuring,
and guiding the dynamics of our systems. The definition:
"STEADY-STATE" is the eventual stabilization of our aquatic
systems, where the system evidences constant observable
behavior as a result of constant input factors.
Deviation from the established biological definition:
The aquarium hobby must directly factor in non-natural
and other directly controlled constant inputs, such as
air pumps, light, nutrients, water changes, etc. These
are not factored inputs in determining "steady state"
for natural systems.
In the real world, "steady-state" is achieved as "old-growth"
or otherwise mature ecosystems with potentially no change
for very very very very long periods of time (until the
next disturbance). No constant inputs are directly factored
in by resource managers, because the natural environment for
any ecosystem is roughly constant, for all practical purposes.
This is the power of our aquaria systems: We control the
environment. Nobody controls the environment for 160
acres of north-facing slopes in the Sierra mountains.
(Micro-climate modification is too transient and thus
irrelevant for this discussion.)
Of course, according to this definition, our systems have an
enormous number of potential "steady states" (many more than
in the "real world". A "steady state" in the natural world
is largely non-determinate because:
Even with relatively constant fixed inputs, chaos at the
right moment in a system's evolution can drastically impact
the end result (refer to my previous post on eco-type
establishment in the Pacific Northwest of the USA).
Aquariums get that too. However, the aquarim hobby has another
combinatorial explosion potential for "steady state":
Unlike the natural world, the aquarist is fully able to select
exactly what those constant fixed inputs are. Unlike the
natural world, we determine artificially and exactly the
CO2 ppm, lumens amount and duration, nutrient levels, fresh
water changes, etc.
>} >In this sense, you certainly can have "too much"
>} >of any of them [light, CO2, nutrients, etc].
"You can force a state-change (away from the desired state) by
providing additional inputs of any of these factors [light,
CO2, nutrients, etc.]"
> It would seem based on existing evidence that I am suffering
> the dreaded "out of balance" problem on my 180gal show tank.
"It would seem based on existing evidence that I am suffering
from an undesirable [steady] state in my 180gal show tank."
* or *
"I am not happy with the results I get with the inputs I
NOTE: If the system is in flux, call it a "dynamic state".
If you observe the system at a plateau (no change with
time), it's a "steady state".
> Given I have optimum levels of measured CO2...
"Given I reached my desired levels of measured CO2..."
* or *
"Given I reached the maximum ppm of CO2 (maybe 15-30 ppm) that
aquatic plants can utilize..."
> the only thing that
> I have come up with is a problem with my micro-nutrients.
I'd say the same thing. Or, that my micro-nutrients might
be the limiting factor for better growth (the limiting
factor to getting a desired state change).
> For a while it seemed that actually turning down the
> lights to 6-8hours a day helped several of the plants and the
> production of algae.
Said exactly right: We forced a state change by modifying the
light input. The result was a new state where some plants and
algae increase in growth rate.
> Of course the problem with defining a "balance" with so many varables
> that are present in these systems is difficult at best.
Insert "steady state" for balance.
True. In fact, steady-state (or balance for that matter) IS
NOT DETERMINATE as a result of input parameters. Recall
the evolutionary formulation of systems mentioned above.
However, we can often predict future states with known input
factors (even with very high precision and accuracy.)
We can often measure the surplus, though: Light hitting
bare substrate, available nutrients in the water, etc.
We can also measure the relative importance of any one input:
Increase/lower the concentrations of any input (relative to
its availability) to determine the sensitivity of the system
to that input. Subtle changes to inputs (up or down) is our
greatest tool to coerce desired state changes.
> I suspect that some of the varables are more important than
> others in defining the proper balance.
"I suspect that a given system state is more sensitive to
some inputs for shift to a resulting state."
> Although, I orginally thought that light and CO2 were
> the biggest drivers in the system, I am not so sure anymore.
Terminology is consistent (I wouldn't change it).
> Seems that if any part of the system is really out of wack
> the entire tank is effected.
Perfect. I might substitute "out of proportion" for "out of
> Of course the challenge is to figure out which ones are bad.
"Of course the challenge is to figure out which inputs are
out of proportion for my current state."
> } I'm hoping that a discussion of the issues involved will help
> } us come up with some sort of guidelines about what combinations
> } of light, CO2 and nutrients go well together, and why.
Right. We are looking for guidelines on proportions. More
specifically, we are looking for guidelines on proportions given
the current system state and the desired system state.
For example, do you feed, do water changes, and add nutrients
to a cycling tank just as you would an established tank? Of
course not. Specific proportions are only relevant to the
current state AS COMPARED TO THE DESIRED STATE.
> } It would be even better if we could also explain what is
> } likely to happen when we deviate from this optimum
> } mix, and why.
"It would be even better if we could also explain what is likely
to happen when we deviate from this maximal set of inputs, and
[Author's note: I believe most people on this list use the
term "optimum" to really mean "maximal" or "maximum amount".
While "maximal" accurately describes the extreme end of
a spectrum, "optimum" must subjectively refer to the extreme
end of a spectrum while factoring in personal preference
(such as tolerance for waste, willingness to deviate from
the maximum possible sustainable biological activity, etc)]
Ok, I've had my say. I've made my peace. Sorry about the
--charley Fort Collins, Colorado USA
charleyb at gr_hp.com or charley at agrostis_nrel.colostate.edu