Ok, general question on CO2....

[Lonewolfblue]

What is better, disolving CO2 into the water column or using mist? I noticed some people are saying that their plants are doing better since switching to the mist method. What are all your thoughts on this...

 

[Glenc]

I am trying the mist in my 10 gallon and I'm getting pearling like I have never seen. I believe the mist is easier for the plants to use as it collects on the under sides and tops of the leaves, even the stems. I think it just saturates the plants with useable CO2 faster. I have only been using the mist for a week, but the improvment in plant growth is quite evident, and again, the pearling is just beautiful. I'll have a better idea in a month, but I'm loving it so far!

 

[MiamiE]

Does anyone have a link to this misting method and what is needed?

 

[mr funktastic]

ya i second that. i have heard alot about it but dont understand how it works.

 

[Lonewolfblue]

Basically, it's just running the CO2 through a fine airstone, such as limewood, and have it placed under the intake of a powerhead to kick the fine mist throughout the tank. And having the fine bubbles go into the powerhead, you don't have the noise like you do when just injecting CO2 bubbles into the intake and the impeller smashes the larger bubbles.

 

[Thebluyak]

3rd it, the mist method sounds interesting, right now im just running it into m xp3

 

[mr funktastic]

so just geta fine mist of bubbles from an airstone and run it under the out take of a filter or powerhead? seems kinda simply compared to all the inline reators and powerhead contraptions out there.

 

[Lonewolfblue]

When I get my reactor, I'll be running my CO2 into the reactor, but the excess that gets caught up by the vent, will get vented out into a powerhead as a mist, which will get kicked through the tank. And since I have an extra output on my manifold I'm getting, I just might try running it on the other end of the tank to my MaxiJet 600 as a mist at a much slower bubble rate. But I'll also be watching my ph levels too, as I don't want too much CO2, if you know what I mean. lol.

so just geta fine mist of bubbles from an airstone and run it under the out take of a filter or powerhead? seems kinda simply compared to all the inline reators and powerhead contraptions out there.

Powerhead is better. Runnning it into a filter will disolve more of it. If you want real mist, then just use a powerhead.

 

[Plantbrain]

There's an old debate, well, not that old, maybe a year or so now, but something I've observed for over a decade, just never considered it in the context that I presented it in prior.

It's something rather difficult to measure, other than indirect methods such as measuring the CO2 and O2 meter readings from one tank with and another without and generally the same set up type/plant biomass/species etc.

Most folks see increased growth.
Very few don't.
Generally current plays a big role in the distribution of the mist sinjce the idea is to have the gas pahse contact the plant underwater in a mist, rather than dissolbving the CO2 entirely into the water.

Some gas does get dissolved, but obviously the water immediately surrounding the bubble as it dissolves is going to be much higher in CO2 than elsewhere. That's a safe assumption.

Gas also transfers across a boundary layer 10,000 times faster.
So it's diffusion coefficent is much faster than a liquid pahse.

The concentration factor is also much higher than 30ppm, (that's the lowest it will ever be in solution that is 30ppm already, since partial pressure will equilbrate the same gas ppms in the solution into the bubble), CO2 does dissolve rapidly, but the it is not instantanous either, and the bubbles hit the plant leaves and the dissolved CO2 also surrounds the plants as well.

You cannot use C14 tracers to see what goes where since the phase of the gas/liquid changes with time.

You can maintain a constant CO2 ppm dissolved in water, and then apply the mist to one tank, and then use O2 ppms as a measure of plant production.

The mist tank tends to have 20-40% more O2 (120% O2 vs 140-160%).
So that means the mist can increase plant growth by about 15-30% more growth with this method.

Some folks don't like the intense pearling, some love it.
Still, I think folks need to see what max growth looks like as a guide for comparisons.
It's simple and cheap to try out and any enhancement with CO2 is a good thing, given 95% of the algae related issues are CO2 related.



Regards,
Tom Barr

 

[czcz]

What is better, disolving CO2 into the water column or using mist? I noticed some people are saying that their plants are doing better since switching to the mist method. What are all your thoughts on this...

Fwiw, in terms of plants I don't think there's any contest. Within a couple days I see the effect of directional mist on plants that were previously stunted or leggy, then have healthy new growth that matures into longer, larger leaves with better color. I think its possible to solve the issue with these plants, but frankly its really easy just to stick them in mist

This is not to say I find regular diffusion ineffective: I think it works great and in many ways prefer it. I find the mist itself distracting and prefer the aesthetic of total/bubble-free diffusion. However, in these set-ups I do find it harder to grow certain plants.

 

[Plantbrain]

Fwiw, in terms of plants I don't think there's any contest. Within a couple days I see the effect of directional mist on plants that were previously stunted or leggy, then have healthy new growth that matures into longer, larger leaves with better color. I think its possible to solve the issue with these plants, but frankly its really easy just to stick them in mist

This is not to say I find regular diffusion ineffective: I think it works great and in many ways prefer it. I find the mist itself distracting and prefer the aesthetic of total/bubble-free diffusion. However, in these set-ups I do find it harder to grow certain plants.

Well said.
I think your observation has some good points there.

"Within a couple days I see the effect of directional mist on plants that were previously stunted or leggy, then have healthy new growth that matures into longer, larger leaves with better color. I think its possible to solve the issue with these plants, but frankly its really easy just to stick them in mist "

This is a more observational method to see if it works or not.
Some detractors have claimed they can grow plants just as well without it, and that the increase in pearlign is just sticky bubbles of air/N2 gas etc.

But you can see the plants grow better and the hard wimpy plants turn into literal "weeds".

You know the nutrients are non limiting, plenty of light etc, but the plants don't seem to grow at 30-40ppm of CO2.

Getting a good handle on CO2 measurements and using RO reconstiuted will rule out such variation.

You need top be able to measure the CO2 ppms in the mist and the non mist tank.

But mist is brute force CO2, direct mainlining.

A few folks have observed, I'm not one of them, their tanks had no effect from mist, but often they did not try it with good current or perhaps something else was limiting their tank's growth(PO4 etc).

If non limiting nutrients and light are provided, then you should see an effect as long as you have good CO2ppm in addition to the mist.

That might also be why they did not see the effect as well, they only used one method tht was under powerwed for their size tank etc.
Whereas the CO2 reactor that was used prior, was properly running.

the best way to judge the mist is to add it to an existing CO2 system and blast the mist around the plant beds.

Then see in terms of plant growth, or if you have a Dissolved Oxygen meter, that would be better.

Regards,
Tom Barr

 

[czcz]

You know the nutrients are non limiting, plenty of light etc, but the plants don't seem to grow at 30-40ppm of CO2.

Getting a good handle on CO2 measurements and using RO reconstiuted will rule out such variation.

I find this particularly difficult to deal with. I can meet these requirements of EI or approximate PPS's method or certain gurus, and pick up things that work along the way, and I grow plants lots of people agree are hard. But there's stuff I only grow nice is mist. Certain Rotalas, Eriocaulon, Tonina, L. "Cuba." I can keep stability and increase dissolved CO2 as my variable, I can lower KH, I can tweak my dosing, I can cheat with Excel, but these plants still look best in mist. My easier plants - like E. diversifolia, L. brevipes, R. rotundifolia -- look awesome in mist. So, depsite my relative inexperience, I feel confident plants like mist.

There's lots of methods I have yet to try, of course, but it's hard to grasp how aquarists experience no difference with mist.

But mist is brute force CO2, direct mainlining.

the best way to judge the mist is to add it to an existing CO2 system and blast the mist around the plant beds.

I like this philosophy/explanation of brute force, and I think mist on top of a traditional diffusor is the best method. I have pointed CO2 mist into problem areas of a tank, and suddenly don't have a problem any more. I will put problem plants into mist to get them to perk up. In my growout tank, the layout is centered around the mist powerhead's flow, it works so well

I figure someone good with layouts could exceed his CO2 target at the diffusor, keep high flow, then strategically place glass diffusors/mist around such problem areas. I remember your tucking the diffusors on the Behemoth in the back, but I mean more of a tech meets nature / out in the open kind of way. Since mist causes focus on the equipment, not nature, we may as well show off cool diffusors as part of the tech.

I am also of the opinion current is very important, for more than CO2.

I struggle with catching up to the N2 part of the mist argument, and get the gas exchange part. Without proper testing equipment and with my amateur understanding of these concepts, I can't contribute much, of course. I still think its painfully obvious brute force is a valid, effective method for CO2. If we all agree CO2 is the most important variable -- assuming light, nutrients, etc -- why wouldn't we blast it onto our plants at great force in high concentration, then let them dissolve there?

If the exact why of mist is isolated, I hope it can be implemented without having bubbles fly around the tank, but I doubt it. Thats still a deal breaker for me: I just don't like mist all over the place -- I'd rather have mist from plants alone. I still think of mist as a farmer's or photography-based/professional aquascaper's method.

(edited for grammar, clarity, etc.)