Is the referenced article available online..?

Yes,
Richard mentioned it did come up in the post here, I posted it
elsewhere though and it was fine for some reason.
:
http://www.s2.chalmers.se/~tw/DOWNLO...ate_limits.pdf

It's heavy read, extremely dense like most research articles, this is
justa review though, so they are mainly comparing things based on the
salient research that's been done to try and make a consensus.


No doubt about it and this is why I'm used to state for well
cycled (fishless cycled) tanks..

Well, since plants use NH4 directly, I've never had to do a fishless
cycle because the plants circumvent that process.
Also, one may simply add NH4 to a bucket and run the Filter in that
for 2-3 weeks or less if add mulm from an established tank or seed
water(dirtier the better).
Same deal with a marine system.
Adds precisely what is missing from an established cycled tank:
bacteria and organic matter.

Somehow us folks managed long before the Web existed and Fishless NH4
cycling was suggested
Why wait?

I don't.
Waste of time and testing.
I did not get into this hobby for that.
Did you?

Well I do respect you to be a very engaged (natural)
scientist but "significant" does _always_ correspond with
statistical methods.

Yes, it means that you can "see a difference" in this case.
If it subtle, it still might be significant from a control, but hard
to see.

Unfortunately I do know enough about
scientific ecotoxicity tests to realise that it's in my
mind not always that goal-oriented (target-aimed?) it
should have to be..

No need either, others do such work, you do things that they don't and
as a while group we can get a lot more done and do the different
things we enjoiy

You should test what you __say__ before saying it. Common
sense. Then you discuss it and see what seems most
reasonable, then test that and so on...........

Well when I decided to enter my very first aquaria group on
usenet I made the decision to be a hobbyist only..

Many do, but then they suggest and say stuff that they have never
tested, experienced or questioned, they just accepted it as truth
because someone wrote it or said it.

I'm much more skeptical and have good reason to be, many of the things
folks claim about aquatic plants have been false.

I often wonder all the things that are said in the hobby
and why folks claim authority etc, when what they say is
often shallow at best, and out right wrong at worst. So I
test to see. If I cannot show that, I propose an
alternative hypothesis that makes more sense given the
observations and go from there.

But aquariums are unique and multifactorial systems. How to
validate such results..? Statistical methods..?

Nope, isolate one thing at a time.
All I have to do to disprove a hypothesis, say excess PO4 will induce
an algae bloom, is show that when I add excess PO4, say 2.0ppm from
KH2PO4, to an otherwise stable healthy control tank, I do not get any
algae bloom.

It does not prove what causes algae, merely what it cannot possoible
be a cause.
This is called falsification. A hypothesis should be testable, if you
cannot disprove it through good well thought out test, then you
tenatatively accept the hypothesis as a possible cause perhaps and
keep trying to disprove it.

The problem arises that many hobbyist are unwilling to test, and
potentially destroy a tank in effort to answer a question. I cannot
blame them. Many folks with problems in their tanks are also hardly
candidates for good control and stable tanks to use as a starting
point. Again, they will believe anything in efforts to find balance/
cure/assumptions.

So essentially it does not matter all the multiple factors all I need
to do is show that for one parameter, say NO3, that high levels, say
50ppm have no impact on a wide range of common aquarium fish that are
known/assumed to be NO3 senesitive species such as Discus, Apistos,
Rose line barbs etc.

I provide good assumed levels for all the other parameters(also easy
to do with RO water and Ferts + large frequent water changes and
accurate calibrated test equipment).

That's more work than many are willing to do, I fully understand that,
but it's what needs to be done to show cause and not mere speculation
and guessing based on ignorance.
I do not give advice based on speculation if I can help it and if so,
I make it clear, it is speculation.

I also seldom tell folks to use test kits etc and other micro
management methods.
I do them, but I use them to answer specific questions about a few
possible causes I think I might be able to answer(with some luck and a
lot of work).

I might never arrive at the ultimate truth or cuase, But
..........I will get a lot close than the folks caliming
things without even bothering to test them to see for
themselves.
NH4 can be add
NO3 can be added
NO3/NH4 can be added
Organic sournce of N can be added that are transformed
into NH4 first.
That way you can tease apart who's doing what and find the
real culprit.

Sorry I guess (my) life is too short for all that crap.. ;-)

Yes, mine as well, but I've been doing this for well over a decade, so
I've picked away at it answering one question, disproving one cause
and heading on to the next.

In my mind probable effects (reduction to NO2)
of high ppm'ed NO3 were the main problem..!

Well, that implies fish waste, not KNO3 dosing.
I agree, very nasty stuff, for plants also.

BTW: Are you eventually "power filterer" and "vacuumer"..?

I do both, plus massive water changer.
I need no test kits since the tank is "reset" and any detritus is
removed.
I alos plumb my tanks for the water change so it backwashes the
filters, I hate cleaning filters and hate doing water changes.

I have the systme set up with a hard plumbed water line in and a drain
out, all I do is turn a few ball valves to change water, no hoses, no
buckets, no effort etc.

I save mysef no less than 60 hours a year of labor and am much more
likely to do a large water change knowing it takes little work. Also,
doing a large water change allows me to work on the tank easier
without sloshing water all over, which is important is deeper tanks
and when gardening.

So the added cost/effort to add a hard plumbed semi automated system
is well worth it for myself.
Even if I paid myself 5$ an hour, 5x 60 = 300$ per year per tank. Adds
up quick and the end result is a much more stable tank that's also
easy to maintain.

Marco

Regards,
Tom Barr
www.BarrReport.com