# Cheapest CO2 ever



## ruben (Aug 11, 2004)

You can get a cheap CO2 system, all you need is a
12v - DC transformer, a rod of stainless steel, 12 carbon (graphite) rods (used for cutting iron, I got them from a welder, 1/4 X 12"), 2 rubber stopers, rubber bands.
insert the rubber stopers in the stanless rod, place the carbon (graphite rods) around the stainless rod (spaced by the rubbers), secure them with rubber bands, connect the (+) side of the transformer to the graphite and the (-) to the stainless rod.
If it's working you'll see a lot of very small bubbles.
I used my HO train power pack, at about 5 VDC the system worked ok
my tap water has a pH of 7.2 KH 2, in 12 hours the pH is 6.2. (tank is 400 liters), I connected the power pack to a pH controller.
I hang all from the hood and it is inserted in the aquarium.
20 graphite rods cost me (in Mexico) about 2 dollars, they lasted 32 days.
the stainless rod cost me 1 dollar (1/4" x 20 inches)
allready had the power pack, no idea on price
rubber stoppers (?)

When rods get old they become soft (half of some of them, dissapeared, the side facing the steel rod) and later some carbon (dust) went to the aquarium, the filter took care of that (that was the time to change the graphite rods), plants/fish not harmed


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## Milan (Jul 6, 2005)

I would highly doubt those bubbles are CO2. What you are doing is called "water electrolysis". By passing an electric current through water you are separating bonded hydrogen and oxygen from it.

2H2O --> 2H2 + O2

One would never like to have free H2 in his tank. It's highly flammable/explosive too.


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## ruben (Aug 11, 2004)

This has been discussed a lot in other forums, the reaction produces CO2 plus H2; O2 reacts with the graphyte and CO2 is generated; the H2 produced is minimal and there's no danger of explosion. I tried to ignite the gas and it it hardly noticeable (my tank has no cover, the hood is 60 cm high) if you accumulate a lot of H2 it would be a risk but the quantity produced in this way is minimal.


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## bigstick120 (Mar 8, 2005)

Sounds like a home made Carbo plus to me


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## Raithan Ellis (Nov 13, 2005)

bigstick120 said:


> Sounds like a home made Carbo plus to me


Exactly! This is a viable option.

http://www.thekrib.com/Plants/CO2/electrolysis.html

However I do recommened safety precautions with playing with DC voltage in water. It can stop your heart.

Regards,
Raithan O. Ellis


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## SnyperP (Dec 10, 2004)

You can buy a knock off carbo+ unit for about 25 dollars. Carbon replacement blocks are ..I believe $10. I know it's more than the dyi, but for alot of people the little extra assurance is worth the money.


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## ruben (Aug 11, 2004)

A hearth stop with 12vdc? that's new for me, in many instances we sacrifice dogs and other animals (I'm a Veterinary Pathologist), 110 v ac (+ anestesia)takes a while to do the job, once I read that if you use dc you need at least 400 v.
Yes, the system is a cheap option for carboplus, prices are much higher in Mexico and also the pleasure to build something...


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## random_alias (Nov 7, 2005)

How do you regulate the level of Carbon being introduced into the aquarium?


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## SnyperP (Dec 10, 2004)

PH controller. Ingenious, but it does add to the "cheapest co2 ever" =p


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## Milan (Jul 6, 2005)

I'm not trying to criticize or discourage your inventiveness, but what really makes me skeptic is the H2. Not so much because of a potential explosion hazard, as much as it being present in the tank free. Electrolysis produces 2 times more H2 than O2. How toxic is H2 to flora/fauna? Does it react with something else (can't think of it meeting Cl)?
On the other hand, how effective is the CO2 production in this fashion? Does all O2 react with C, or there is a portion (and how large) going elsewhere?

And finally, how do you diffuse the CO2 produced?

On most of this I don't have answers, so if someone could chime in, great ..., but to me they are valid questions.

BTW, I highly doubt your controller is taking accurate readings on the pH in a tank with electrolysis going on.


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## Raven_ (Dec 5, 2005)

sounds very interesting.
i seriously doubt h2 is of any problem.

perhaps with the aquarium sealed tight above it could be flammable but a few small ventilationholes fixes that just fine.
H is lighter than air so it tries to go up.

and for h2 in the water doubt it is a problem there too.
the only way H can react as i know is by fire and then producing water.
not a chemical expert so might be wrong.

might try it out on my little experiment tank.

ruben, how much faster does the vegetation grow ?


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## DurendaL (Sep 8, 2004)

Maybe H2 it's not a problem, but what with ...

C + O2 = CO2	
or C + ½O = CO
1½O2+2C = CO + CO2

What with the second reaction. CO is very danger.


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## ruben (Aug 11, 2004)

Plants are doing great, they continue growing and pearling (i,ve got about 50 plants), In the past I used compressed CO2 but got bored from leaks and trips to refill.
The CO2 bubbles are so small that they dissolved in the way to the surface.
Yes pH lectures vary a lot if I place the probe close to the rods, the aquarium is 2m long so I've got plenty of space.
H does not dissolve in water, it is not a problem for plants or fish
I doubt you can produce CO since is an incomplete C oxidation product, the possibility of Cl ions presence in a fresh water aquarium is dobtful Cl is to reactive to be present in this way.
Not all O2 will react with C to form CO2, some of it escapes to the surface.
I undestand your skepticism, I'm not a Chemist and I can't answer all the questions (also I'm not an English native speaker, as you might noticed) but the system works for me, yes the pH controller adds a lot to the price, it is not a must but a nice addition to any aquarium


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## Gumby (Aug 1, 2005)

Could it be a possiblity that the H2 going into the water would combine with free oxygen to produce H3O+ (hydronium ions) which would cause the pH controler to give a false reading? After all pH is a combination of concentrations of H3O+ and OH- ions. Now that I think about it... maybe the H2 being produced could produce OH- ions as well?

Is there a chemist in the house?


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## ruben (Aug 11, 2004)

I was really bad in stechiometry, I can't tell you about the reaction it might be something like 2H20 -(this should be an arrow)- H2 + 2O2, I understand that Hidrogen is not reactive and it dissolves poorly in water, as I told you before if you place a match on the surface the gas ignites (although it is hardly noticeable); Yes the reaction causes misreadings in the ph meter, if you place the probe close to the rods you get strange and unstable readings 1.1, 5.2 etc
Placing the probe about 20 cm from the rods the readings stabilize.


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## Gumby (Aug 1, 2005)

Hydrogen is actually fairly reactive. Even in it's diatomic state(H2) it can react with considerable ease because hydrogen bonds are farily weak (can be broken via heat).

Check this out: http://www.chemsoc.org/viselements/pages/data/intro_hydrogen_data.htm


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## ruben (Aug 11, 2004)

Hydrogen won't dissolve in water, the article says H is very common but not very reactive


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## jrtiberius (Dec 1, 2005)

Dude, I would really like some pictures and maybe some diagrams... if you have any. This fascinates me.


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## ruben (Aug 11, 2004)

Unfortunatelly my camera is not working; however is very simple to do, place the steel in the center and the carbon rods around, I used 2 rubber stoppers as spacers and rubber bands to hold the carbon rods in place.


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## sayembara (Dec 13, 2005)

could you draw, please? (MS Paint)


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## ruben (Aug 11, 2004)

I hope this helps, I used 12v DC from a HO train, the connection is above water http://img.photobucket.com/albums/v326/ruben65/Electrolisis.jpg


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## oceanaqua (Oct 24, 2005)

Dude...too small.


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## ruben (Aug 11, 2004)

I'm sorry, I hope this helps, the center rod is of steel, the rods around (I used 12) are carbon rods, the spacers are rubber fawcet gaskets, connect the positive side to the carbon rods and the negative to the steel rod, you can use a carbon rod instead of the stainless, the effect is the same


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## sayembara (Dec 13, 2005)

thanks for the illustration


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