Do you know why I refer to it as the 'herd mentality' or 'herd
behavior'? Because most people in this forum (and most people that I
have discussed the topic with) perform water changes ONLY because
everyone else is doing it.

Really? What has convinced you of that? Thus far, the only thing I've
seen to that end is that you've cited errors at Wayne's site wrt valence
state and number of oxygens on nitrite, nitrate, and ammonia. Despite
those errors,

One person stated that they change their water because they enjoy it.

did you also find the underlying theory of the nitrogen cycle
to be somehow un-sound?

Nitrogen cycle unsound? Your kidding me right? The nitrogen cycle AND
denitrification are the reasons behind NOT having to do water changes.

Not evidence, but context. Qualification for, and quantification of, the
information you offer.

My tank size is a qualification for NWC? How? My tank size provides
quantification for NWC? Please explain.

Meaning, do you use your sump as a refugium, to grow algae(s) as a
supplemental means of nutrient export? If yes, what are you growing?

No.

http://www.reefland.com/rho/0105/main2.php

1/2 way through that article, you'll find a pic and discussion about the
Chaetomorpha that blackhole is using to export nutrients.

Not necessary IMHO.

fish species/size? (I'm not sure how this qualifies as evidence)

It quantifies the fish mass (and the corresponding amount of waste) which
can be handled without the need for water changes as a means of nutrient
export.

If my waste exceeded the metabolic capabilities of my bacterial load than
wouldn't my ammonia or nitrite or nitrate demonstrate this? As I stated
already, they are all 0ppm (LFS test kits).


inverts species/size? (I'm not sure how this qualifies as evidence)

It identifies whether or not the species you are keeping are relatively
robust, or prone to problems related to less-than-perfect water quality
(as, ofr example, some SPS corals are famous for).

I stated already that my fish appear healthy. Why do you insist on taking
this discussion in circles?

recent water test results?
Do you track water parameters regularly? I use to, but always same
result. 0ppm Nitrate, nitrite, ammonia. pH normal range. Observe any
fluctuations? No

You stopped after only 2 years?

No, I have not done a water change in over two years.

I'd slow down if things looked to be under
control with a tank, but I'd test aboutmonthly, since water parameters
usually change in advance of health issues with the occupants. Since
you've stopped, please consider a quick look at your current water
parameters, just to verify that, today, you have the same results you did
when you last tested.

Equipment setup (skimmer, lights,powerheads, sterilizer, carbon, phos-
reactor, other filtration etc)? (I'm not sure how this qualifies as
evidence)

I'm trying to establish/understand the conditions under which you've
obtained success with NWC. If there are other filtration factors/methods
at work in your system maintaining water quality, I'd like to know about
them, please.

Skimmer. Live rock and sand. Period. I supplement with Kent marine
essential elements.

Lights and powerheads go towards general suitability of comparing your
results to those of a reef system with inverts. If, for example, you only
maintain flourescent lights for observing your fish, then you might expect
that low light is also helping to control your rate of algae growth. With
some SPS reef systems running 4-6 Watts/gallon of broad spectrum Metal
Halide lighting, smaller changes in water quality become larger problems
with algae growth, as the algae has all the light it needs to grow
prolifically.

Feeding schedule? (I'm not sure how this qualifies as evidence)

As with fish mass, it helps to understand how much of a nutrient load your
system is handling, without the need for water changes.

Read above about ammonia, nitrate and nitrite. Again, I am getting the
impression that you are taking this discussion in circles.

My inhabitants appear healthy. I am certain that they would not
appear unhealthy to you.

NP. Forget the picture. I'll take your word that all of your occupants
are healthy and happy.

Oh, Man! Did I forget two BIG ones!

How much live rock (pounds), and/or live sand in your system(depth in
inches)? What kind of live rock (point of origin)?

I don't remember the total pounds. I use to buy a little at a time. I
didn't keep track. Sorry. Sand is roughly 2-3 inches.


What does your detrivore cleanup squad look like (hermits, snails,
sandsifters, etc)?

1-hermit crab. A few snails.

That's what makes this thread so sad. If you understood why water
changes were not needed (at the biological level) you would understand
how really simple (not rocket science) this topic is.

Please expand on this idea. I want to understand, at the biological
level,
why water changes are not needed. Take me through it, step by step,
please.

Again. I am pretty sure we have been through this already. Ammonia ---
nitrite----nitrate----N2(g) + H2O. (Enzymatic conditions via bacteria.)

To give your discussion context, my understanding of chemistry is
good enough that I've built a successful career on it

Me too!

The former implied to me that anyone anywhere (with a FOWLR or reef setup)
can quit their water changes, starting today, without deleterious results
on their system.

You would need to gradually stop water changes. I think I stated this
already too! (CIRCLES)

The latter implies that the way in which you transition
from WC to NWC requires some education into chemistry/biology before doing
so, and thus NWC may _not_ be as simple as the first quote implies.

No, it implies that those that do water changes don't know why they do them.
If they knew what was going on at the biological level (see above), they
would know why it isn't necessary.


I think you are right about water changes, to a certain extent, but
i'm a bit more cautious about which setups I would consider NWC for,
especially reef type setups.

My experience has directed me to the following conclusion (again, take
it or leave it): Water changes weaken your bioload. Bacteria exist
in your aquarium that take care of ammonia, nitrite AND nitrate. The
end result is N2(g) and H2O. I would suggest stopping your water
changes gradually (gauge by testing) to allow your bacteria to
proliferate.


My experience tells me that there is an upper limit to the load you can
place upon the bacterial colony in a tank.

How many experiments have you performed? How many conditions have you
varied? Is this anecdotal data? A little hypocritical eh?

I accept that NWC change systems are reasonable and certainly possible, but
I suspect that you need
to start (and possibly maintain) them on the low end of the total load to
a
tank's bacterial colony. At this point in time, I'm trying to get a feel
for where your tank fits into the range of possible bio-loads.

BTW, I've usually seen the term "bio-load" as an expression of the amount
of vertebrates/invertebrates vs. tank/system size.

Bioload is directly proportional (in general) to the bacterial population.
Increase bioload, and increase bacterial population (proliferation).
Decrease bioload and you will decrease bacterial population (again, this is
a generality).

So, when I state that "Water changes weaken your bioload", this is what I am
referring to. Water changes lower bioload thus lower your bacterial
population (less to metabolize = bacteria cell count drops).

A larger bio-load means
there are more fish in less space. You seem to use the term differently.
Could you post a quick comment on how you use the term?

See above.

Lets NOT go in circles anymore. I have presented my case ad nauseam.