[APD] RE: CO2 and tap water

["Thomas Barr" <tcbiii at earthlink_net>]

> > I've been through this discussion before and no one could explain to me
> > where the gasses for super-saturation come from.
>
> I'm curious too!

Ultimately it's coming from the rainwater that seep through the soil, as it
does this, bacteria in the soil give off lots of CO2 which is imparted to
the water, this gas cannot escape to the air above as the water seeps
deeper into the ground water table. Caves and formations are formed due to
this acidic CO2 laden water and most all well water is rich in CO2. This is
where the CO2 is from: soil bacteria as the water passes through the ground.
Cold water holds more gas(all gases, not just CO2 or O2). So when you warm
it up, it outgasses. 
Most ground water and tap is much colder than folk's tanks. So there's some
effect there.

> So if I'm seeing bubble production dependant on plant species and the
amount
> of light, do you think that is an out-gassing event?

Generally not, mainly means that the you are not adding enough CO2 to begin
with.
Some can be due to outgassing but not inside the plant itself unless you
increased the temp of the plant.
O2 outgassing from warming tap can occur but I think this is short lived as
far as influencing the plant's pearling.  

If you do not see at least say 50% the same pearling normally near the
end/last 1/2 of the day, you likely are not adding enough CO2.
The pearling you get there is a max rate of pearling/O2 evolution. So use
that as your standard.

I'd suggest to ignore the O2 super saturation effect from the tap and
assume the CO2/PO4 is causing it.
You can add high O2 100% pure gas to investigate this effect of super
saturation, which I have.
Likewise you can dose 100% pure CO2 into the water and see that effect. 
Then you can decide with out influences from other gases such as both CO2
and O2 together=> who's doing what? You do not know unless you keep them
separated. 

I'd say you get most of all that pearling from CO2/PO4 maybe, but generally
if the plants pearl and looks better after a water change=> that means you
need to add more CO2. Large water changes show this effect more than small
ones and frequent water changes help add enough CO2 for a day or two each
week which is better than barely enough once every 2-4 weeks.  

> Is there a mechanism whereby the Carbon (or maybe some other element?)
from
> the minerals in the water is being utilized to directly or indirectly
> stimulate the growth process?

Yes, PO4 may be present in the tap water.
You can add PO4 to see if the same effect occurs when you dose KH2PO4 later
in the week right before your next water change.
If everything else is present in good amounts, a water change with high CO2
and PO4 will kick pearling into very high gear.

Regards, 
Tom Barr

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