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: Wed, 11 Oct 95 14:33:30 MDT
In-Reply-To: <199510101939.PAA03000 at looney_actwin.com>; from "Aquatic-Plants-Owner at actwin_com" at Oct 10, 95 3:39 pm
Mailer: Elm [revision: 70.85]
> >krandall at world_std.com (Karen A Randall) said:
> >You will _always_ have problems if light. CO2 and nutrients are
> >not in balance. In this sense, you certainly can have "too much"
> >of any of them.
> Shaji <bhaskar at bnr_ca> responded:
> From what you say above, balance seems to be some function of light,
> CO2 and nutrients. Also from what you say above, balance is
> apparently not the same as "long-term, trouble-free growth of plants".
> Do you have a more precise definition?
I have an opinion. :-) Did I mention also that I am wordy and
long-winded? :-) :-)
It is true that "balance" has no wide-spread biological
definition. If I was forced to define it, I would probably
state, "Balance is that point when all factors in the system
become the limiting factor simultaneously." Of course, this
is a somewhat arbitrary definition based on preference. That's
my definition because I'm a tight-wad and I don't like the idea
of wasting too much of any one factor. For me, the system isn't
in balance if I'm wasting too much of any one thing. An equally
valid definition would be, "Balance is that point when system
deltas (system changes) are minimized or severely restricted, as
the result of at least one limiting factor other than time".
This is a little more esoteric, but probably more appropriate
to the universal scientific audience.
The REAL problem here is, "What do we want to balance?" This
is *not* something we can universally define. We must go through
the exact same process that one would go through to determine
the *personal* economic "opportunity cost" of any action or
inaction, which (of course) is different for each individual.
"Do I balance plant growth with the highest possible fish
population?" That *might* be measurable. How about "Do I
balance these two plant species, (with different light and space
requirements) and what is most visually pleasing to me,
against the highest possible fish load?" Forget it. It can't
happen. You will never quantify that in any reasonable manner.
Most sciences dwell upon the measurable. If we can't measure
it, then relegate that to a "symptom" and address it (or describe
it) in another manner. The term "balance" is hopelessly
arbitrary, and is thus scientifically irrelevant.
Most biologic resource managers don't ever address the concept
of "balance", but prefer to refer to the dynamics of a system with
a concept of "state-shifting", or "steady state". The reason
for this is simple: When we are not (readily) capable of
measuring the end result, we must revert to measuring the
deltas (the changes) that we are able to observe in the system.
When there are no deltas (no "state shifts"), then we must have
achieved the end result (a "steady state"). Take-home message:
DELTAS ARE SCIENTIFICALLY MEASURABLE.
For our aquariums, this means the following: Which plants do
well, and which not? Is algae and undesirable vegetation able
to effectively compete with the desired vegetation? All
aquarists have a mental picture of the desired result, or
"steady state" that they wish to achieve; the process
is only to force state-shifts until we achieve the desired
result (and hold it there in a relatively "steady-state"). We
modify the system factors (light, temp, CO2, nutrients, etc.)
until we are able to force an outcome (a "state-shift") that
is closer to the desired system state (the desired vegetation
does well, undesirable vegetation and algae are not able to
compete). Thus, the REAL goal is to bring about a "state
shift" which may require more *or* *less* of any give system
inputs. When we get to the desired state (and are able to
maintain it for an arbitrary period of time), then many aquarists
can imprecisely claim to have reached "balance". I say
"imprecisely" because resource managers still do not have
concensus on what "balance" means (and is probably different
for each person).
This concept of "state-shifting" is not purely academic; it
is tremendously practical. Because my ears have grown sensitive
to the accurate selection of precise terminology, I would prefer
to hear people mention they have, "...reached a steady-state
that is particularly desirable, GIVEN THE SYSTEM INPUT
PARAMETERS" as opposed to state they have "reached balance".
That's just me, though--I can get by with any terminology,
We know we are "state-shifting" when we observe some species
on the advance and others on the decline. A very obvious
example is the cycling of a new aquarium: some species do well,
others not so. Algae blooms, then recedes. Plants requiring an
established substrate suffer, then (possibly) prosper. The
species composition and their individual (relative) successes
will change with time as we manually intervene, so we *must*
consider the manual intervention as a *real* input to the
For many aquarists, the goal is (perhaps most accurately)
described as a "steady-state" system of desired vegetation
(and each aquarist can define what that state is). This usually
means desired species do well, algae cannot compete, and we
still have enough open areas for the occasional fauna resident
(fish). As stated in the previous paragraph, our manual
intervention is an appropriately measured factor in this
"steady-state": We can call our system "steady-state"
merely if there is no species compositional shift over time,
and we are happy with the system input requirements.
If that is accomplished because we do five water changes a week
or none, prune regularly or not at all, the term "steady-state"
can be directly observed and applied. Some species may be
doing very well and some barely maintaining a maintenance
existence; However, if all continue to be represented in
equal proportion, the system is awarded "steady state"
For our purposes, however, most aquarists want to reach that
point where we do not have to manually intervene (significantly)
to remove algae (or do whatever). This implies the "steady-state"
should be a result of "acceptable" intervention, not "unacceptable"
intervention. Thus, the definition of the "steady state" can
be partially dependant on the levels of intervention the system
requires (manual or otherwise: remember, nutrient additives are
usually "acceptable" intervention in a system that may truly be
considered "steady-state"). For example, the definition of
"steady-state" for the commercial system may be an enormously
high bio-load that they can maintain with daily algae cleaning
and enormous water changes, while "steady-state" for the home
aquarist may imply algae scraping once a month.
In all of this, I imply that the "steady state" we achieve
is the "desired steady-state". We could have a system that
maintains an algae bloom indefinately, but we typically
interrupt the system's factors to force a deviation to
an alternative (more desirable) "steady state". The process
to get there, of course, is "state-change".
Of course, we don't always want a "steady state". The simple
introduction of a new species or re-definition of the
vegetative plant scape implies state deviation; however,
the happiest (and most knowledgeable) aquarist will oscillate
between any number of "desired dynamic states" without spending
significant system time in an "undesired dynamic state".
As before, all system states are determined as "desirable"
or "undesirable" through the observer's eyes (but usually is
entirely dependant on wanted and unwanted species).
(I want my crypts system or my cabomba system, but I
don't want algae in any of them. I may change my plants
from time-to-time, but I don't want to lower my fish load.)
In these cases, many aquarists are REALLY moving among desired
states, never into undesired states, and might still call
their aquarium "in balance".
> Is balance to you a yes/no proposition (i.e., either there is balance,
> or there isn't)? If so, how do we determine from a set of conditions
> (light, CO2, nutrients) whether we have balance or not?
Personal preference. :-) How much work do you have to do to
get what you have? I can make a good argument for the following:
if( work_and_inputs_required < benefits_achieved )
/* We think we have balance. */
/* We don't think we have balance. */
> Or, are there different degrees of balance? if there are degrees of
> balance, how can we compare one set of conditions (light, CO2,
> nutrients) with another and say which of the two is better?
You hit the crux of the issue: You CANNOT EVER compare those
sets of conditions for "balance" and determine which is "better".
Even if you could get an answer (which I doubt), it would be
different for the next person. I would have hard time stating
a 20 foot deep reef aquarium is "in balance" when we must use
submersible MH lighting to keep the reef alive. That sounds
horribly un-natural and un-balanced to me, but may be perfectly
acceptable input for the next person.
You have balance, or you don't. You have steady-state, or you
don't. However, there are degrees (but degrees are only
measurable from the steady-state point of view.) You can be
measurably closer or farther to a steady state, simply because
you can plot the rate of change in the system. (Guess what?
It's an asymptotic curve).
> How does "out of balance" as a function of light, CO2 and nutrients
> translate to "problems"?
For "steady-state", this would translate into "state shifting"
("state change") in the aquarium. If you are already unhappy with
the current state, this could be good (or worse). If you already
have a desired steady state, this is almost always bad unless you
are actively directing movement to another desired steady state.
Like most mutations, random deviation from a working system
ALMOST ALWAYS leads to a less-working (or non-functional) system.
Insert "desired" for "working" in the previous sentence and
read that again. This can only be combatted with intelligent
(directed) intervention or through the compensation of geologic
time awarding "success" (through survival) on some systems and
not others. Unfortunately, most of us do not have geologic time
on our side (and the wife certainly does not allow that kind of
time). Re-read this paragraph and find the other option.
> The above are hard questions with no perfect answers. 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. It would be even better if we could also
> explain what is likely to happen when we deviate from this optimum
> mix, and why.
Clearly, there is no "optimum mix". I have a hard time with
"optimum" because that term has EXACTLY THE SAME PROBLEMS as
Cheer up, though: You can address all (relevant) aquarium
problems directly and measurably by looking to established
practices among biological resource managers. Not all research
has been done and not all problems are solved, (I don't know
the number of lumens over how much time allow crypts to
metabolize 90% of a certain amount of nutrients in direct
competition with algae) but many of these professionals are
very good at defining and encouraging (and measuring) state
shifts to desired directions.
A VERY NICE thing about aquaria is that we (essentially) really
do have an entire functioning system through which we can
effect desired change. The magnitude of this power is amazing
in such a small box (because we don't need 40 acres of land).
The current state of natural resource management all over the
world is in turmoil, however, because there is an enormous
difference between viewing systems in a static manner (which
they are not, which does not work well, and which cannot be
measured) and viewing them with dynamic and changing states
(which these systems have [more or less], which works better,
and which is measurable). Quite often this distinction is
evidenced between the general public (static perception) and
resource managers (trying for a dynamic perception).
Take home message: THE AQUARIST WITH THE STATIC VIEW LOSES (or
spends all Saturdays on the aquarium).
"Must you be so linear, Jean-Luc?"
(said by Q to Captain Jean-Luc Picard in "Star Trek: The Next
--charley Fort Collins, Colorado USA
charleyb at gr_hp.com or charley at agrostis_nrel.colostate.edu