Re: [APD] Fe and GW

[Thomas Barr <tcbiii at yahoo_com>]

Bill wrote:

"Tom said, "I've heard this for years and to date I've never
been able to
induce any algae of any sort using trace elements."

Here's how you do it:  Into a well-planted, stable, fairly
heavily stocked
20 gallon aquarium, pour about 2 ounces of Flourish.  Wait a
day.  The water
will be a lovely shade of green.  Wait a few more days.  It will
disappear. Of course, there are many other variables involved.

Now coincidence isn't causation, but I just never get green
water.  I have
many other kinds of algae, of course, but never that.  The tank
in question
has been clear since that episode.

Bill"
===================

I never had GW either till I added NH4 at high light.
I've been adding high levels of traces the entire time I've been
in this hobby.
More is better was something I thought as well and never had
reason to doubt that adding high traces causes harm and made
sure there was enough.

Then took that relationship with NH4 and extended it to fish
waste, soil, slow down in growth(say after a few weeks of high
CO2(35ppm), drop it(say 5 ppm) for a couple of days)and thus
uptake of NH4 that is being produced, anything that cuases a
pulse of NH4 into the water column or backup of NH4 assimilation
from bacteria into NO2/NO3 or plant biomass.

I've done this a number of times for each group of NH4 related
treatments. At lower light, many cannot produce GW. Other algae
tend to be induced but slower. We get more variation of the
timing and species induced as well as light drops. 

To prove cause is difficult, but the relationship is highly
suggestive of it in light of any other alternative hypothesis.
I have on the other hand, been much more successful at
determining what something is NOT.

That's a much easier question to answer and rules out other
alternative hypothesis such as "Does excess Fe = algae?".

I've added 200mls of Flourish to a 20 gallon tank and let it sit
for a week.

No algae. No shrimp deaths, no fish issues.
The water was tea colored.
Note:this amount is 200mls/59mls higher than your suggestion,
333% higher and 7x longer with no ill effect noted.

Lighting is 450 umols, quite high.
It was a waste of Flourish really.

Addign much more 5-10mls to such a tank over a 2-3 day peroid is
a waste for that matter. Not sure why you'd add 59mls, but
still, you did and I added a lot for another reason, the person
taking care of the tank messed up when I took off for a week. 

For your tank:
My bet was slightly lower CO2 than optimal could induce the
greenwater, and adding Fe to a Fe limited tank will certainly
drive photosynthesis faster, limiting it thereafter would also
slow PS down. Thus CO2 uptake take was faster when you added it,
leading to low CO2 and slightly stunted plants=> downregulated
NH4 use(Cannot use it if there's no carbon frameworks to attach
it to) once the supply of CO2 drops too low for the plants to be
efficent at NH4/CO2 uptake.

Plants just do not go merrily along full blast unless there are
non limiting nutrients and stable conditions.
If you add Fe and get algae, you likely have a downstream effect
occuring.

I can see this and am confident, much more than you, that this
is what occurs in this tank. It explains why my tank does not
have algae when I repeat this test and why yours does after you
add it and why the algae goes away thereafter.

Do you have an alternative hypothesis that is more plausible?

This is a common downstream effect when a limiting nutrient is
added to the system.

And it's also a good example of why you have to be careful
ascribing cause to correlation.

When we added PO4, that drove PS(photosnythesis) faster and
folks assumed that high PO4 = algae.

But adding the PO4 with non limiting CO2 did not.
Several folks confirmed this and I'd been doing it all along
without ever measuring the CO2 or PO4.
But I did know then that PO4 was not the issue.

I did not know it was CO2 until.........I tested it:)
So testing is pretty important.....not for just diagnostics,
rather, to see what is really going on and to be sure you are
not being influenced by confounding factors.

Try bumping the CO2 up some and adding the Flourish again.
See if you can prove this to yourself(since it obviously
interest you).

I've seen this correlation monkey business start a dozen
myths(K+, Ca++, Mg++, NO3, about every nutrient there is, but
oddly few focused on CO2 other than my nagging self.....) and
I've chased them each down and beaten them to the ground.
 
Regards, 
Tom Barr

www.BarrReport.com 




 
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