Confused on CO2 mist

Re: Confused on CO2 mist

CO2 mist is not about dissolving efficiency, it's actually counter to that.
That is part of the controversy for many.

It's about delivery of pure or near pure CO2 gas to the plants directly, rather than adding very diluted 30ppm in a thick visicous medium, water.

Even if a pure gas bubble hits the plant leaf once every 5 minutes, that's still far more than the 30ppm in the water and the rate of diffusion is much more rapid into the plant.

It's very tough to prove that the CO2 that enters the plant is CO2 dissolved in water or in the gas phase. I'm not sure how to show that, so I'm not even going to touch that quagmire but I know another way:

So rather than that method, I've approached it from a O2 plant production as a measure of increased growth. You can measure the CO2 ppm levels in any two tanks for comparisons. So if they are close, then the mist is the main variable. You can even do something like this in a tank, see how well the plants grow near the mist outlet without blasting the mist all around the tank.

This is pretty damn clear data and folks can visually see the difference when done right.

Folks that claim it does not work or that I'm nuts simply have not tried this approach nor looked at the pearling and O2 level difference.

It's plain as day. I doubt I can prove the gas vs the liquid gets to the plants better, but I can show it does produce better growth.
Some folks have added the mist to a reactor, that works also, but.......you should simply use the venturi reactor is that is your goal, cheaper, simpler etc.

Does essentially the same type of thing.

Regards,
Tom Barr

 

Re: Confused on CO2 mist

Sure, that works, I use the stone at the bottom rear and have the spray bar vertically mounted so the mist gets blasted with hardly any view of it in the tank.

Regards,
Tom Barr.

 

Re: Confused on CO2 mist

I know what you are saying, but how small do these bubbles need to be thus how small does the mesh need to be?

You'd need similar flow rates, but something could be done perhaps.
I'd rather stick with the O2 levels.

That does not lie and also relative growth rates do not either.
No hobbyists have even done RGR's for our plants when comparing a method etc also.

It's not that hard either.

REgards,
Tom Barr

 

Re: Confused on CO2 mist

Yes, the preferred method.

Regards,
Tom Barr

 

Re: Confused on CO2 mist

The claims on either side will not be resolved by chasing bubbles and monitoring gas.

I've used the mist to successfully grow marine plants using air alone.
No reason why this would not also work here with pure CO2 gas.

Mist and the measured CO2 level(even if it's not absolute, eg the real CO2 levels, you only need a pH before and after) should be kept close together as far as pH.

Several species of fast growing plants should be used.

The O2 levels alone and pH can give you all the info needed, but the RGR's would back it up pretty good also.


Regards,
Tom Barr

 

Re: Confused on CO2 mist

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

 

Re: Confused on CO2 mist

But it does seem obvious it is not more efficient, you can see bubbles being wasted and floating around up to the surface some.

Regards,
Tom Barr

 

Re: Confused on CO2 mist

Well, there are some engineering studies on micro bubbles in ocean systems, not a simple model to say the least.
It's beyond what I am willing to get involved in directly.

Rather, I am going to address it on a more practical method, the plants are the test kit.

What might seem efficient, might be less so and what might seen less, maybe more.

Hard to say, but assumptions really will get you into trouble if you assume too much and accept previaling dogma.

That is road I've been down many times.

It's been a mud fest here in CA, been working to dig stuff out.
We are not waiting for FEMA here

Regards,
Tom Barr