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Re: [APD] CO2 gas, water changes and plant growth Vol1
What was the null hypothesis in the experiments?
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----- Original Message ----
From: Thomas Barr <tcbiii at yahoo_com>
To: aquatic-plants at actwin_com
Sent: Friday, January 26, 2007 8:21:47 PM
Subject: Re: [APD] CO2 gas, water changes and plant growth Vol1
> > What is in air that's not at high levels in the tank that
> > induce intense growth?
> > CO2 in the gas phase.
> What causes you to assume that the causation is due to
> exposure to any
> particular substance in the atmosphere?
Err, something called O2 levels afterwards:-), and that fact
that CO2 is the only **likely component** that will increase a
photosynthetic rate in a significant amount that's in the air,
that's less available in the water?
I would add, "suggest", not "causation", maybe "tentatively
What is your skeptical alternative hypothesis that you can
reasonably suggest is causing a 60% rise in dissolved O2 levels
and that this is incorrect? What test have you done that
increase O2 rates in aquatic plants by 60%?
Have you done this test yet??
> information it
> is equally plausible that the stress of being exposed to air
> increases the metabolic rate of the plants.
**Stress decreases O2 rates**. It does not increase O2
production rates in aquatic plant production/growth.
For plants to produce more O2, they need have the photosynthetic
machinery driven faster, stress reduces this, not increases it.
Decoupling the light//dark reaction by many aquatic herbicides
is their mode of action. We see dramatic declines in O2
production upon treatment and it is rapid. Other stresses such
photorespiration, a common stress in plants due to light/lack of
CO2 etc reduces O2.
At a given high non limiting light level which I have in this
If you reduce with supply of CO2, the plant will down regulate
the light reactions and you will not see much O2 production.
If you increase CO2 supply, the plant will up regulate the light
reactions and produce more O2.
A temporary boost is not seen in stress related responses since
the light reactions are the first step and where O2 is produced
by the D1 protein.
This is why many growth parameters use O2 and CO2 uptake for
their direct measure, fluorescence is another method that can be
used on live plants and is commonly used in relative units for
herbicide impacts on weeds and non target plants.
It is also why O2 levels are used to measure aquatic plant
productivity in Limnology.
> > This shows/strongly suggest that aquatic plants can
> > increase production and growth if they are supplied with a
> > phase of CO2.
> There is no evidence of that yet.
There is now.
I used an Oxygen meter and measured the before and after
treatments with the mist vs the same dissolved CO2 levels. About
40% higher in 7 tanks.
This does "show/suggest" such evidence. You say that there is no
evidence and I've provided it. Rather than argue semantically,
try testing it yourself.
You will learn much more by doing rather than being an arm chair
Same tap water, same nutrient dosing, lighting was the same and
measured with a PAR meter(I can raise my lighting to change the
PAR). CO2/O2 both measured by standard methods. Biomass and
different species variations are present and make the test more
realistic, but about an average of 40% increase with a range of
28% to 52%, so that's far from insigninficant differences even
if you account for errors in the methods. The CO2 error was
about 4ppm but I have slightly higher CO2 in the control tanks
to account for that, so the actually O2 difference might be even
So there's some errors, all data has some, but the difference is
quite dramatic and significant, more so than the difference
between adding PO4 to a limited tank vs not, and everyone has
little issue accepting that adding PO4 helps:) The O2 rate there
is only about 5-20% in very limited PO4 tanks.
Still, we can see dramatic pearling increases there upon adding
PO4 to an otherwise limited tank.
You could say the same about adding nearly every nutrient and
argue against every one of the nutrients we add.
There's no "proof".
There are many things that go unaccounted for etc ad nauseum for
everything, not just this but for light, for nutrients and for
But what have you done to answer the questions and test them
rather than refute everything? Not much near as I or anyone else
> > It's a simple test and the observation #1 shows that it's
> > due to degassing tap water etc, it's due to the gas phase
> > exposure to air.
> Exposure to air may cause pearling, or it may be a rapid
> change, or five minutes without dissolved nutrients, or any
> number of
> possibilities not yet controlled for.
If no nutrients where present, one could only assume, that would
be a stress,not something that increases O2/plant growth.
Temperature cannot be a factor as the room temp, tap water make
up and the tank water are all the same 75F. I do not use
heaters. Make up water is the same temp as the room.
> > So I tested the before and after O2 levels at the same time
> > did the water change above. I had 7 ppm(100% a tad over)
> > and 11ppm after(t= 2 hours) or about 160%.
> You succeed in demonstrating that the plants aren't pearling
> out some
> other gas like helium, and that the production of that gas is
> after the water change. This doesn't get us any closer to the
> cause of
> that increase.
It becomes a semantics game, you never will arrive at absolution
or ultimate truth and answers with this line of reasoning,
that's just the way science is, it's just a construct, it's
never going to give 100% absolution, but it does work rather
well. So you can keep asking for more evidence and more, that's
But why not ask why folks add CO2 at all? Or NO3? Or PO4? Or
Show definitly that adding Traces helps improved measurable
growth and that it is not just something else?
So Jerry, please tell me why you think the dissolved O2 meter
measure 60% higher? What do you think it is?
Why do others also see it? Why do you think other things such as
air exposre also show similar patterns?
Maybe we are not seeing the same things? Maybe we are imagining
Just blind luck that I'm getting 28-52% increases in O2? And 60%
Try holding yourself up to your own standards.
How do we really know and have proven that traces truly help?
Under your standard, we do not.
So why bother telling folks to add it?
> > As far as I know, this is the first demostration without a
> > meter to show and confirm that pearling in this case was due
> > gas phase exposure to CO2. The backup with the O2 meter
> > more support for the contention as well.
> That plants pearl after a water change doesn't confirm that
> exposure to
> gaseous CO2 is the cause. It only confirms that plants pearl
> after a
> water change. There are hundreds of variables present that
> aren't being
> controlled for.
I'll concede it does not "confirm" 100% but in light of an
alternative.........Since you assume there are hundreds, what
makes a plant grow 28-52% faster after this treatment?
What else sounds like a good reason that we see an dramatic
increase in O2 levels?
What is your best guess?
Have you done the experiment?
I can add CO2 mist and also see dramatic increases in O2
production, I can expose the plants to air for a short peroid
and also see the dramatic increase in O2.
We can not add CO2 at all and see dramatic decline by about 10X
less in O2 production.
Light, temp, water make ups are all similar, dissolved CO2 was
similar between treatments.
Plants grow with 3 basic things in aquatic systems:
Light CO2 and nutrients.
These largest players where addressed and controlled for.
Sure, I could carry on about endless possibilities, any research
paper, thesis, dissertation can, and never get anywhere if we do
not make some assumptions at least. You have to cut the that
questioning off at some point and go with it.
The most likely candidate is all I have to work with in light of
a better alternative. Maybe one will come down the pipe someday,
but I do not see hardly any hobbyists doing such test any
I've show a dozen different test over the last year and all
point to the gas phase increasing O2 levels which are a direct
correlative function of plant growth. You can also see the
pearling differences and you can see the plant biomass growth
differences, it's like asking folks to prove that adding CO2
truly helps the plant's growth rates or not.
Most accept that it does, but you have not proven it?
Other folks have switched over to CO2 mist and seen dramatic
intense pearling, it's not just me, it's everyone that tries it,
and a few have not seen improvement which given the other
factors, is common. But most do get dramatic pearling and
growth. and not after water changes, but see similar effects.
Trying some rather simple water change routines and noting the
effects can tell folks more about their plants, CO2 and how to
improve their tanks/plant growth.
The folks that have switched over and tried the CO2 mist as well
as this large water change method, have noted a common
observation. Same with exposure to air. Even if you do not
accept the reasoning behind it, the observations that it helps
is rather clear.
Given that plants grow for 3 three main areas: light , CO2 and
nutrients, what else is there that might cocnsistently day after
day increase the O2 levels so dramatically and pearling?
Simple question after all.
Show you are right or at least close and able to rule something
out through testing. It's just all gas otherwise.
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