re:Balance and lighting

>From: krandall at world_std.com (Karen A Randall)
>Date: Sat, 14 Oct 1995 19:04:28 -0400
>Subject: Balance and lighting 
>> Karen, balance is a term for which I have no good definition, and
>> my science background, I just *have* to ask.
>> From what you say above, balance seems to be some function of 
>>light CO2 and nutrients.
>Do you not agree that these things must be supplied in a balanced 
>way in order to avoid problems?

I agree that these must be supplied, and that the proportion is
important.  The intent of my article was, however, to find out more
about what exactly you meant by balance.

>> Also from what you say above, balance is
>> apparently not the same as "long-term, trouble-free growth of 
>Why not?  I would consider any tank that has achieved long-term 
>trouble-free growth to be in balance.

Yes, long-term trouble free growth implies balance, but balance (if it
is considered to be some relationship between CO2, light and
nutrients) does not imply long-term trouble-free growth (You could
have a tank full of algae instead, because the conditions for growing
plants and algae are similar.)  Both the criteria I listed above have
to be true for "balance" and "long term trouble-free growth of plants"
to mean the same thing.

>> Do you have a more precise definition?
>Well, from my art rather than science background, I think of 
>balancing a planted tank as I do balancing a mobile.  There are 
>many, many possible variations.  on any axis of the mobile, you 
>must achieve a state of balance.  This can be done by adding more 
>weight to one end of your support piece, lightening the other end, 
>or moving the balance point between the two.  

I like Charley's objective definition of balance/steady state: all
measurable factors stay within some narrow range.  In my mind, these
factors include not only light, CO2 and nutrients, but also plants,
algae, fish, etc.  I really like the fact that this definition of
balance does not have subjective notions of good or bad.  It also
applies equally well to fish-only tanks, reefs tanks, etc.

We can then begin to talk subjectively about "good" and "bad" balances.
A tank that is in balance with lots of algae is not desirable.  If low 
intervention is required, that's good, and so on.

>>  If so, how do we determine from a set of conditions
>> (light, CO2, nutrients) whether we have balance or not?
>Let your eyes tell you!  If the fish and plants are healthy, and 
>growing well, and algae is at a manageable level on a _sustainable 
>basis_ (and I'll quantify this here by saying sustainable for at 
>least a year or more)  the tank is in balance.

This is where you and I still seem to have differences.  Presence of
algae to me does not imply that the tank is not balanced.  It could be
balanced, but in an aesthetically unappealing way.

>This is not a static balance, however, because it is a closed 
>system.  One of the items to be balanced is the the work the 
>aquarist is willing and able to put into the system.  That too, 
>will vary depending on the situation.

I'd like to leave the "amount of work" out of the definition of
balance, and instead put it in the subjective discussion of whether 
a balance is good or bad.

>> How does "out of balance" as a function of light, CO2 and 
>> nutrients translate to "problems"?
>The problems are as varied as the systems themselves.  Algae 
>problems are often a result of an imbalance between light and 
>macronutrients, but could also be caused by too much light and not 
>enough CO2.  Too much light without sufficient CO2 can cause 
>serious pH swings, but this can become even worse in the presence 
>of plants that are particularly adept at splitting cabonates.  Too 
>little light on a tank planted with light hungry plants can cause 
>a failure to thrive.  Lack of a specific trace element can cause 
>deformed growth.  Plant eating fish in the tank can cause holes in 
>the leaves.  Shall we go on?<g>

In retrospect, my original question was poorly worded.  The problem I
have is that you seem to be assuming that all problems can be traced
to some imbalance between CO2, light and nutrients.  This is not true,
in my experience.  It's possible to have a good blend of light, CO2
and nutrients and still have lots of algae. In that sense, "problems"
and "imbalance" are not the same thing.  This goes back to the "Is
balance the same as good healthy plant growth?" issue.