Re: Confused on CO2 mist
FrankG said:
Tom,
That could be a hard requirement to meet. I would assume that after a while the mist bubbles will consist not only of CO2, but will reflect the relationship of the dissolved gases in the water column due to the diffusion that takes place. Therefore, some of the CO2 will dissolve in the water column, but at the same time oxygen and possibly a small amount of other dissolved gases will enter the mist bubble from the water column.
That does not change the fact that with this method, submersed plants have access to CO2 gas and dissolved CO2. And based on my personal observations, I can confirm that growth is phenomenal.
Regards,
Frank
Well yep, the rate of diffusion is very limited due to the transfer of the liquid solution to a gas state, so the notion that other gases diffuse into the bubble is not a very strong arguement.
Recall that the diffusion from gas to the water is roughly 10,000 times slower, now reverse this the other direction(the rate constant should still be the same as well as the boundary layer thickness/distance). The rate would be very slow, which is why they use aerators, O2 injection, wet drys etc.........to degas the water, rather than having it occur instanteously due to diffusion of partial pressures alone..........
Degassing into the air above(or INTO the bubble) is not a fast process either.
Funny how naysayers are on a one way street.
If the CO2 is 10X higher in the water, more CO2 will tranfer into the bubble also. So even if the all the gas in solution is the same as the bubble, you still have a much fast rate of transfer in the
gas form versus the dissolved water form.
No?
I mean let us accept the naysayer's arguement.
Assume that all the gas in the water and the bubbles are in equilibrium.
Assume it occurs instantly(we know this does not happen, but let us assume for a moment to indulge them even more).
Since the gas is still at 10X higher CO2 levels, the issue now is if the gas vs the liquid forms diffuse faster correct?
Now we know the diffusion constants for gases vs water, they are about 10,000x faster.
So the plant still gets the CO2 at a much faster delievery rate, even if the concentration is the same.
I'd rather breath Gas than a thick heavy liquid, plants and diffusion are no different.
But now if you go back and add that extra CO2 left in the bubble, now you can add that concentrational difference back into Fick's 1st aw.
Still, 3000ppm in gas solution of CO2 is pretty juicy.
And that is at equilibrium.
Adding 1,000,000ppm of pure CO2(or nearly pure) into the gas, will really get it going.
Even if the bubble lost 90%, what about the 100,000ppm?
And why doesn't those little mist bubbles persist when they rise? We can watch them disappear, so there is not a lot diffusing into something that's disappearing either.
You cannot have both on that issue.
Blah, I'm going back to RGR, and O2 levels
:gw :gw
It revolves around fick's law, but I'll let some physicst mess with it that likes micro bubbles in solution, I'm more interested in better aquatic plant health.
As you and most anyone that has tried it can attest, our eyes are not lying, nor are our plants. That's growth and you can see the dramatic pearling.
Once you see this and see that you can maintain that pearling all week long, you know something has to be causing the growth.
Adding CO2 in this manner has to provide the plant something, even if the naysayers claim otherwise, they can not disprove nor prove what they are saying, merely add doubt, that's not much use.
I tried to approach the gas bubbles in larger terms, but that is not the same as a micro bubble unfortunatly. It really does require some techincal equipment.
Regards,
Tom Barr
