# [Wet Thumb Forum]-Aerobic CO2 System



## EraN_RozeN (Aug 15, 2005)

Hi everyone...
I have an idea for a CO2 system that allows the yeast to breath oxygen.
This causes an increased CO2 production and for a longer time.

The system consists of two 2 liter bottles.
One bottle will be with an open top so the water surface will be maximized and the other will be closed with the CO2 output pipe connected to it.
They both will be connected at the bottom so the water levels in them will be equal.
It's kind of hard to describe it so here is a sketch of the system:
http://grm.m.walla.co.il/briefcase/00f3/e/r/a/n/_/r/o/z...9402/Aerobic_CO2.JPG

As the water and air are in a state of gas equilibrium with one another, the air will slowly dissolve into
the water and will equally distribute in both bottles.
In this way the yeast will has sufficient air and will not produce alcohol which kills the yeast.
I know that some CO2 will be lost because of the open bottle but the closed one is supposed to
produce more CO2 then the "usual" closed bottle.

I would like to hear comments and ideas about this system.
I didn't build it yet but i think it will work great!


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## imported_russell (Sep 14, 2004)

it could work, but i would think that all of the co2 would escape through the open bottle. just my thought though. it seems like it would be easier for it to escpate that way than through the tiny hose.


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## Roger Miller (Jun 19, 2004)

You never really know what will happen until you try it out. I can think of two problems you might want to be ready for if you do try it.

First, air diffusion in water is slow. You won't get an even distribution of oxygen in the system. If the yeast are active and and there is no circulation in the system then most of the water will be anaerobic despite the free surface.

Second, the system is open to air, so the CO2 produced will be under atmospheric pressure. A couple different things can happen in a CO2 reactor. If the CO2 outlet is in a stream of moving water then the pressure at the outlet will probably be less than atmospheric pressure and the low pressure will tend to suck the sugar solution into the aquarium. If the CO2 outlet is not in a stream of water then it will be under hydrostatic pressure greater than atmospheric pressure. There will be no CO2 flow into the reactor unless the CO2 pressure builds up in the closed bottle side of your system. Pressure buildup on the closed side could displace liquid out of the open side of the system.

I imagine that the best case is where the CO2 outlet is in a moving stream but the pressure is not low enough to pull the yeast solution into the CO2 delivery line.


Roger Miller


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## imported_russell (Sep 14, 2004)

i say give it a try though, just watch it and be careful. i would use lower water levels in the jugs just in case it builds up and tires to push water out the open bottle as roger says. you never know if you are on to the next new strategy with diy co2.


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## imported_timlawyer (Jul 14, 2003)

Seems like a really interesting idea. How about this...what if you had a regular CO2 diy reactor (like a 2 liter soda bottle) with the output for the CO2 and then added an input tube that connected to a air pump on the outside of the bottle and an airstone set below the surface of the yeast/sugar/water mixture. If you set the air pump on a timer (say to coincide with the lights) wouldn't that create an input of O2 for the yeast to utilize and result in increased pressure for an increased CO2 output volume/pressure during the daytime? Am I explaining myself well? What do y'all think?
timlawyer


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## EraN_RozeN (Aug 15, 2005)

Hay everyone...
I am glad reading all your comments.
I was sure i will be answered with things like "Are you out of your mind"!?  (just kidding)
Now I've got more time on my hands so i will try to make this and will keep you posted on how things are going.


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## imported_Left C (Dec 5, 2003)

How are you not going to have any alcohol produced? When yeast eat sugar, they release CO2 and ethyl alcohol. How in the world is your solution going to get around this?


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## EraN_RozeN (Aug 15, 2005)

When providing oxygen to the yeast they do not produce alcohol at all.
You can read in this article about it: http://www.qsl.net/w2wdx/aquaria/diyco2.html#3

In aerobic system:
Glucose + Oxygen -> Carbon dioxide + Water + Energy

In an anaerobic system:
Glucose -> Carbon dioxide + Alcohol + Energy

This what makes all the difference.


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## imported_Left C (Dec 5, 2003)

I know that yeast makes CO2 and ethyl alcohol in anerobic conditions. That's Biology 101. I've never heard of yeast making CO2 in aerobic conditions for aquarium use.The last paragraph of "Tips on Mixtures" in your 'read this' discusses a problem with using aerobic conditions as to how to get only CO2 into the aquarium and it also says that (ethyl) alcohol is also produced.


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## Roger Miller (Jun 19, 2004)

Left C,

I think you misinpreted the article. It says that we use an anaerobic system to get a pure CO2 product and have to put up with alcohol because we are using an anaerobic system.

What the author overlooks is that CO2 produced by yeast in anaerobic water is not pure -- it is saturated with water vapor. Also Paul Krumbholz (I think that's how the name is spelled) showed that CO2-enriched air is useful in aquariums.


Roger Miller


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## imported_Left C (Dec 5, 2003)

Roger,
Thanks
Left C


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## Paulo Pinheiro (Feb 11, 2003)

I think timlayer's idea could work if using a one way check valve but it would also cause entry of massive amounts of air in the aquarium together with the CO2, unless it is a really weak pump, but in that case it may fail to conteract on the pressure created inside the bottle and actually pump some air in...


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## EraN_RozeN (Aug 15, 2005)

I personally reject all methods that introduce oxygen into the tank.

The oxygen damages the ability of the plants to absorb the CO2 from the water.
It also transforms nutrients like Fe into a much harder to absorb molecules.

This is why I want to invent a method that allows the yeast to grow in an aerobic environment but will not introduce oxygen into the water.


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## imported_Left C (Dec 5, 2003)

EraN RozeN,
I know that yeast in aerobic conditions use nitrogen as a food source. I don't remember if it was mainly for fuel or mainly for reproduction. I'm using 0.5ml of Seachem's Nitrogen in a Hagen CO2 kit and I'm using two others w/o Nitrogen to see what happens (as controls).
Maybe you know something about the nitrogen use with yeast.


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