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saurabh_m
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 Posted: Mon Mar 07, 2011 1:41 pm Post subject: Surface Disturbance and Dissolved CO2 |
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Hi!
I have a great confusion. Always it is a presumption that emersed growth is good because plants get proper CO2 from the atmosphere, which means the CO2 level in atmosphere is adequate. Which sounds reasonable since all the plants, trees etc. are taking CO2 from the atmosphere itself.
Now it is said that the water column if disturbed tries to balance the dissolved gases with atmosphere, which I think is an equilibrium of the kind that % of dissolved gases in water becomes same as that of atmosphere. This again indicates that surface disturbance should always bring back the dissolved CO2 levels at normal position, even if the plants consume most of the dissolved CO2, so why is it so that surface disturbance is always a big no-no for planted tanks.
I have seen some tank shots of master aquascapers with too much water movement on the top, which again strengthens my point to some extent, but experience shows something else, whats the matter folks, I'm too confused.  |
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Severumkid
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| Posted: Mon Mar 07, 2011 3:42 pm Post subject: Re: Surface Disturbance and Dissolved CO2 |
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Surface agitation is necessary for healthier plant growth IMO.
If you supply ample Co2 (ready 3-5 bubbles/second) from a steady source, then you will not have Co2 shortage in your tank. Where as putting a power head near the surface gives me strikingly lush plants. I also 10 a 15% water change every day and 60% water change every 10 days or so.
Nice point Saurabh, but your question leads to another question. What will happen if we inject air in the water column? As air is almost 80% Co2, how will the plants react? What do you guys think? |
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sudheerj
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| Posted: Mon Mar 07, 2011 3:59 pm Post subject: Re: Surface Disturbance and Dissolved CO2 |
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HI Surabh & Dev,
I think the issue is that the Saurabh is comparing normal condition with the CO2 supplied tank. In normal case when there is no artificial CO2 supply to the water, then the surface mixing should help in keeping the ratio of atmospheric Co2 in water column( or at least trying for that equilibrium).
But when we are supplying CO2 as pure CO2 from bottom or near bottom of the tank there tend to be a high concentration of CO2 in water which is good for optimal growth of many plants. This spreads across tank by diffusion/ internal currents caused by movements of fish etc.
If we agitate then the higher amount of CO2 dissolved in water tend to escape to atmosphere to maintain the equilibrium. So it think this is the funda of no surface agitation in case of planted tank when there is a CO2 supply to the tank.
with best regards,
Sudheer |
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saikumar
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| Posted: Mon Mar 07, 2011 4:02 pm Post subject: Re: Surface Disturbance and Dissolved CO2 |
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| Severumkid wrote (View Post):
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As air is almost 80% Co2, how will the plants react? What do you guys think?
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Which planet do you live in???  |
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crazzyarchh
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| Posted: Mon Mar 07, 2011 4:03 pm Post subject: Re: Surface Disturbance and Dissolved CO2 |
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Severumkid...
air does not have 80% co2....if i remember it rite it has about 70% nitrogen 20% o2 and a very low % of co2.... |
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Tirtha C
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| Posted: Mon Mar 07, 2011 4:06 pm Post subject: Re: Surface Disturbance and Dissolved CO2 |
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| Severumkid wrote (View Post):
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Surface agitation is necessary for healthier plant growth IMO.
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saurabh_m
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| Posted: Mon Mar 07, 2011 4:07 pm Post subject: Re: Surface Disturbance and Dissolved CO2 |
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| sudheerj wrote (View Post):
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HI Surabh & Dev,
I think the issue is that the Saurabh is comparing normal condition with the CO2 supplied tank. In normal case when there is no artificial CO2 supply to the water, then the surface mixing should help in keeping the ratio of atmospheric Co2 in water column( or at least trying for that equilibrium).
But when we are supplying CO2 as pure CO2 from bottom or near bottom of the tank there tend to be a high concentration of CO2 in water which is good for optimal growth of many plants. This spreads across tank by diffusion/ internal currents caused by movements of fish etc.
If we agitate then the higher amount of CO2 dissolved in water tend to escape to atmosphere to maintain the equilibrium. So it think this is the funda of no surface agitation in case of planted tank when there is a CO2 supply to the tank.
with best regards,
Sudheer
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Correct, but then why is the emmersed growth better. |
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Tirtha C
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| Posted: Mon Mar 07, 2011 4:16 pm Post subject: Re: Surface Disturbance and Dissolved CO2 |
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| saurabh_m wrote (View Post):
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| sudheerj wrote (View Post):
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HI Surabh & Dev,
I think the issue is that the Saurabh is comparing normal condition with the CO2 supplied tank. In normal case when there is no artificial CO2 supply to the water, then the surface mixing should help in keeping the ratio of atmospheric Co2 in water column( or at least trying for that equilibrium).
But when we are supplying CO2 as pure CO2 from bottom or near bottom of the tank there tend to be a high concentration of CO2 in water which is good for optimal growth of many plants. This spreads across tank by diffusion/ internal currents caused by movements of fish etc.
If we agitate then the higher amount of CO2 dissolved in water tend to escape to atmosphere to maintain the equilibrium. So it think this is the funda of no surface agitation in case of planted tank when there is a CO2 supply to the tank.
with best regards,
Sudheer
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Correct, but then why is the emmersed growth better.
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I think you are asking 2 different questions together.
1. Why we don't want surface agitation in planted tank?
2. Why health of emmersed grown plants are better?
right? |
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crazzyarchh
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| Posted: Mon Mar 07, 2011 4:22 pm Post subject: Re: Surface Disturbance and Dissolved CO2 |
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saurabh..
the surface area of the aquarium which comes in contact with the air is very less as compared to natural water bodies, also these water bodies have turbulence which might help in exchange of gases.
other factors like wind might also help.....where as in the aquarium such exchange may not be possible due to smaller area, low movement of water and absence of wind. |
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Madan
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| Posted: Mon Mar 07, 2011 4:32 pm Post subject: Re: Surface Disturbance and Dissolved CO2 |
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Saurabh, the CO2 ppm in water at equilibrium with air is 1-2 ppm. Insufficient for plants.
Surface agitation does increase CO2 back to the 1-2 ppm dissolved levels when plants stop using CO2 at night in a non CO2 injected tank.
Forgive Deb, he mentioned 80% CO2 levels in the earth's atmosphere just after he pulled his head out off a coke bottle.
The same goes for his surface agitation is good bit, except that it does help increasing oxygen levels at night when plants respire,
you'll have to stop the agitation when CO2 injection starts again in the morning.
Not necessary if you have a clean filter + aquarium + healthy growth of plants. |
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saurabh_m
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| Posted: Mon Mar 07, 2011 4:42 pm Post subject: Re: Surface Disturbance and Dissolved CO2 |
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| Tirtha C wrote (View Post):
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I think you are asking 2 different questions together.
1. Why we don't want surface agitation in planted tank?
2. Why health of emmersed grown plants are better?
right?
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But the two questions are related aren't they.
Madan Sir,
Could you elaborate this a bit more, please. Or a link, maybe..... |
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Tirtha C
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| Posted: Mon Mar 07, 2011 5:13 pm Post subject: Re: Surface Disturbance and Dissolved CO2 |
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| saurabh_m wrote (View Post):
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| Tirtha C wrote (View Post):
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I think you are asking 2 different questions together.
1. Why we don't want surface agitation in planted tank?
2. Why health of emmersed grown plants are better?
right?
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But the two questions are related aren't they.
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No... they are different.
Just to add what MAdan Sir has said already. Plants need 30ppm CO2 (Hope I remember this correctly) to grow under water healthy. So if we don't push CO2 then there will be very less CO2 which is dissolving from air. Now when you are pushing CO2, that means you are increasing the level of CO2 in water than the air.
This time, if we start surface agitation, then this extra CO2 will start going out of water and there will be CO2 fluctuations. And we all know why we need a steady CO2 level in a planted tank. :)
But there is another important factor we should keep in our mind. To keep a good health of your aquarium, you need a good amount of dissolve O2 in tank water. If you have big fishes, too many fishes, you will see sometimes they are gasping even when CO2 is not too much. This is because of low O2 in water.
Sometimes we need more than 30ppm CO2 in tank. At the same time if you need good O2 also, install another diffuser connected to an airpump. This will keep adding O2 to tank water without agitating the surface.
In planted tank you need a mild flow all over the tank not a turbulence. |
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sudheerj
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| Posted: Mon Mar 07, 2011 5:17 pm Post subject: Re: Surface Disturbance and Dissolved CO2 |
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Hi Saurabh,
-----Correct, but then why is the emmersed growth better.----------------
Do you think all plants are grown better as emmersed ? It may be some plants which do better in emmersed conditions, it may be a natural adaptation of plants to the seasonally varying levels of water in nature where plants gets partly exposed to air at least in few months during semi/ non rainy seasons.
As a mater of fact below is the composition of air
Dry air contains roughly (by volume) 78.09% nitrogen, 20.95% oxygen, 0.93% argon, 0.039% carbon dioxide, and small amounts of other gases. Air also contains a variable amount of water vapor, on average around 1%
with best regards,
Sudheer |
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Linelogic
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| Posted: Mon Mar 07, 2011 5:24 pm Post subject: Re: Surface Disturbance and Dissolved CO2 |
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Saurabh,
In water the diffusion of gases is very slow and minimal . So even if the water surface that is exposed to the atmosphere get's enough CO2 contact ( 2-3% ), the amount that get's dissolved and diffused into the water layers below the surface is very minimal. Hence we tend to inject CO2 into water, to keep the CO2 at all levels of water high. |
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Madan
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| Posted: Mon Mar 07, 2011 5:26 pm Post subject: Re: Surface Disturbance and Dissolved CO2 |
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Saurabh you want a link for what ? Dissolved CO2 levels in water at equilibrium ?
Just google !
Or for Deb and the coke bottle ? Sorry, I just made that up !  |
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