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Re: [APD] pearling after water changes Vol 2

Folks, I verified several times with a dissolved Oxygen meter.
I have used it in conjuction with the test.
It's not just the pearling tank/air exposure alone and looking
at the pearling, it's measuring with an O2 meter as well. 

Did some folks miss that entirely or what?

Why would replacement water with the same temp and equilibrated
with the air add that much O2?, way beyond saturation values
after the treatment?

Come on, answer that question.
Stop bugging over controls and 100's of possible issues and look
at the most likely ones, this is huge effect, not something
trite and insignificant.

Then address why the CO2 mist test also produce similar,
although slightly lower O2 levels than the air exposure.

These questions are ignored ironically.

It cannot be other other gas that produces the high O2 levels
........because......... the test method test O2! Not other
gases. the pearling is just another obvservation in conjunction
with the O2 readings.

What about this is hard to understand?
I mean it's common sense.

The sticky gas idea is baloney, that was easy to disprove, if
stick bubbles from degassing water, or from other "mystery
gases" where at play here, we'd see ___random evenly___ spaced 
bubbles on everything/everywhere in the tank.

......but we do not. We also do not see high O2 levels with such

We do see a gradient of bubbles starting with the location where
the highest light is, this is true regardless of a water change
as well(normal non water change days etc). When you first turn
on the lights, does pearling occur in the darkest regions of the
tank first or last?

How many of you even own a PAR meter?

Pearling started where the highest light is and progresses
through time. There are no other bubble formation in the test
tank. Just on the plants. Recall, the make up water is the same
temp, and equilibrated with the air. 

Likewise, you can drain and refill with the same water.
So that is what I did, not just one mere observation, not just
mere tank and not one mere test nor observation. I took O2
readings as well at the same time. 
> To find out if the pearling is due to exposure to air, drain
> off the tank
> water, expose the plants to air, and add the same tank water
> back in.  That
> will at least suggest air exposure has something to do with,
> but will not
> confirm it, and certainly will not confirm that CO2 gas had
> anything to do
> with it.

Why else would the O2 levels shoot up well beyond 100% then?
Please offer a new hypothesis as to why that might be? That's
the opbservation, so offer up a good reason why this might
occur? I just calibrated the O2 probe, so that's accounted for.

What other gas/process can make over 100% stauration of O2 in
the tank's water?

There is none I can think of, maybe my brain and are feeble:-)

Only photosythesis can increase the O2 above 100% or adding very
cold water to warm water rapidly, but that was not done.

That leads me to conclude this is an increase in plant growth,
O2 is a direct measure of autotrophic growth in aquatic systems.
It's not some other gas, it's not some other variable.
CO2, light and nutrients, temp etc are accounted for here.

Those are the things that change plant growth. O2 is good
measure of plant growth. Stress generally reduces O2 production,
not increases it.
N2 gas is not going to make aquatic plants grow faster nor
produce more O2.

> My tanks pearl like crazy after a water change, even when they
> contain no
> plants.

And does the O2 level go above 100% also?
Is the make up water accounted for? Same temp, equilibrated, not
mixed and aerated as it's being added?

Do you see a pearling gradiation in the high to low light?
No, you see bubbles all over evenly spread through out the tank.

No so in the test I did and that was the point.
If you accept the sticky air bubble idea, then you'd not see
higher O2 levels and you'd not see the bubbles make a specific
pattern (only on the plant leaves) you could relate to
photosynthesis along a light intensity gradient.

Water change degas bubbles form everywhere, rocks, glass,
filter, gravel, not just on plants.
That is a very simple observation to rule out that notion.

The O2 meter rules out other possible gases and addresses plant
growth rates specifically. So it's not just one test method to
make the conclusion, it's several.

But do not take my word for it, try it and get a O2 meter. See
for yourself.

Try the exposure to air and then try it without, refill with the
same tank water. Measure O2 before and after(expose for 10 min,
then refill and measure O2 levels for the next 2 hours) for each
water change treatment.

Next, try the CO2 mist and turn it on for 2 hours. The next day
measure O2 at the same time of day or better yet, measure the
entire day at 1 hour intervals.

I did. Of course if you do not test or try anything, you'll
never know.

I can make the same arguements about whether we should add PO4,
Fe, ADA gravel etc or not and is it really helpful to our tanks
also. Why not argue against that also?

Why assume that CO2, 40-45% of plant dry weight biomass is any
different? My point is to get other folks to try this, and see
what they think. Then they can test and conclude themselves.
Please do use an O2 meter and test. 

Try and think about the assumptions you have and take another
look with these ideas in mind.

Tom Barr


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