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[APD] why there is an increase in growth with CO2 mist

Laith Arif may have written:

"After following some interesting (and not so interesting)
debates/discussions around the following subjects:

- H2O being water (or not)
- Pianos hanging suspended over heads
- Gravity working the same everywhere (or not)
- Einstein's General Relativity
- Newtonian physics
- 30.0000002 mg/L of CO2 vs 30.0000000 mg/L of CO2
- Doc Martins and their emplacement
- Manure as a substrate
- The behavior of the universe
- Science in the US (or the lack thereof)
- Hostility (or not) to public manifestations of religious belief
- Intelligent Design fiasco (or not)

I'm still curious as to why there is an apparent increase in growth (and
perhaps pearling) with Tom's experiment.  "

After thinking about this a bit when it first come out, I came to the
conclusion that the bubbles could be helping transport carbon across the
boundary layer which surrounds the plant leaves. Another way to increase
diffusion across the boundary layer is to make the layer thinner by
increasing flow. I tested this by placing a powerhead near the bottom of my
internal reactor and directing it as some pigmy chain swords which had not
been growing too well. when I did this, I found a huge increase in growth
and pearling, not only in the swords, but also in the rotala, ludwigia, and
java ferns that were downstream of the swords. (The powerhead is still
there now, 3 weeks later, while I am putting together a new filter system
to increase flow throughout this tank)

If the plants are being limited by availability of Carbon, making more
carbon available to the plant should be a good thing. This could be done
with tiny bubbles (which rapidly equilibrate in carbon content with the
surrounding water due to the high solubility of CO2 in water, and O2, N2 in
a tiny CO2 bubble), or with increased flow which allows faster diffusion of
Carbon across the boundary layer. As to whether C02 dissolved in water or
as a partial of CO2 in the gas phase in a tiny bubble attached to the plant
leaf is more available to the plant, that is a question for the botanists.
My field is physics, not botany.


p.s. I sure wish this list would get away from the endless pontificating
and ranting and direct itself back towards the subject of growing plants

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