[MCSLABS]

Anyone try putting together a CO2 generator using dry ice ? Drawing up plans now for one. We have a grocery store which sells dry ice here locally, would make things easy for sure.

 

[GrampsGrunge]

How you going to store it once it's gone gaseous?

 

[MCSLABS]

Schd 40 PVC is rated at 330 psi. Make up a bank of 2 liter volume with multiple tubes. Use a 250-300 psi blow off. About 80 grams of dry ice should yield around 300 psi in 2 liters. That should be enough CO2 to last a while in a 40 gallon tank.

 

[Seattle_Aquarist]

Anyone try putting together a CO2 generator using dry ice ? Drawing up plans now for one. We have a grocery store which sells dry ice here locally, would make things easy for sure.

Hi MCSLABS,

Dry ice is typically expensive when comparing the volume of CO2 generated per dollar verses buying CO2 gas. Also dry ice is difficult to store. Lastly regulation of the amount of gas generated would be an issue so the fish don't die from too much CO2.

 

[MCSLABS]

Hi MCSLABS,

Dry ice is typically expensive when comparing the volume of CO2 generated per dollar verses buying CO2 gas. Also dry ice is difficult to store. Lastly regulation of the amount of gas generated would be an issue so the fish don't die from too much CO2.

Dry Ice here is around $1 a pound. 1 pound of dry ice is a tremendous amount of gas.

There is a valving issue which I'm working on now, but dry ice is readily available here locally.

 

[mistergreen]

Since dry ice is so easy to get, try setting it up like a yeast reactor. I have not ideA how long it would last or how much co2 it'll generate.


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[MCSLABS]

You could run it 96 days at 2 bubbles per second around the clock for 96 days on 1 pound of dry ice.

 

[MCSLABS]

Since dry ice is so easy to get, try setting it up like a yeast reactor. I have not ideA how long it would last or how much co2 it'll generate.


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I am in new product development at this company and I do tend to over think things a tad and sometimes make them more complicated than necessary. ^^^^^ the above suggestion sounds a whole lot easier to manage. Still got to figure out what to do with excess pressure as it sublimes from solid to gas.

 

[Seattle_Aquarist]

Hi MCSLABS,

Dry ice is typically expensive when comparing the volume of CO2 generated per dollar verses buying CO2 gas. Also dry ice is difficult to store. Lastly regulation of the amount of gas generated would be an issue so the fish don't die from too much CO2.

Hi MCSLABS,

Actually I have to correct my statement. I just "did the math" and:

1 pound of CO2 Solid (dry ice) will produce approximately 12 cu ft of CO2 gas

1 pound of CO2 Liquid (i.e. in cylinder) will produce approximately 9.7 cu ft of CO2 gas

I pay about $2 per pound to fill my CO2 cylinders so Dry Ice is certainly cheaper on a dollar per cubic foot of CO2 basis.

 

[Bushkill]

I don't run CO2 in any of my tanks but good gosh do I love reading DIY threads that really think out of the box. I was neck-deep in SW for 13 years and you just wouldn't believe the creativity over that time span.

 

[GrampsGrunge]

Schd 40 PVC is rated at 330 psi. Make up a bank of 2 liter volume with multiple tubes. Use a 250-300 psi blow off. About 80 grams of dry ice should yield around 300 psi in 2 liters. That should be enough CO2 to last a while in a 40 gallon tank.

I'd be really, really, cautious about storing a high pressure gas in a DIY tank, that 250~300 psi could cause a lot of damage if the endcaps came loose or it structurally failed.

Honestly, this is a really, really bad idea. I've seen the aftermath of someone's attempt to make a confetti cannon using 6" PVC sched 40 blow-off tanks. Is it worth damaging your house or injuring loved ones?

 

[MCSLABS]

I've been rethinking this idea a little, thought of an explosion in the middle of the night is rather distasteful.

I do have a stainless steel thermos, 32 oz I never use any more. I think I will attached a 10 psi blow off and a supply line with a needle valve. I got 4 spools of 20 and 22 gauge PTFE tubing which would cut down flow considerably.

 

[691175002]

If you are allowing built up pressure to gas off, the system will only generate CO2 for as long as it can stay cold. At best you are talking 2-5 days with 99% of the CO2 being wasted.

It is not practical to contain the pressure generated by solid CO2. It would look almost identical to an off-the-shelf CO2 system, except instead of a cylinder you'll need to include some kind of enormous box with a door that can survive many tons of force.

You may be able to store unpressurized CO2 in balloons or something but it would of course need to be stored at near nominal volume.

 

[mistergreen]

yeah, it's best not to seal the pressure without a certified gas tank. You can give it an output where there is no high buildup like a DIY yeast CO2.

 

[KevinC]

Hi MCSLABS,

Actually I have to correct my statement. I just "did the math" and:

1 pound of CO2 Solid (dry ice) will produce approximately 12 cu ft of CO2 gas

1 pound of CO2 Liquid (i.e. in cylinder) will produce approximately 9.7 cu ft of CO2 gas

I pay about $2 per pound to fill my CO2 cylinders so Dry Ice is certainly cheaper on a dollar per cubic foot of CO2 basis.

1 pound of CO2 is 1 pound of CO2 - no matter the phase. At the same temperature and pressure the gas has the same density, so both generate the same volume of gas.

OP: If dry ice is so cheap, I wonder why liquid isn't? It costs less to make the liquid - since compressed liquid tanks are used to make the solid.

 

[jeffkrol]

My last CO2 supplier sold it in tank for $2/lb.
Current one charges $1/lb. Dry ice would offer no savings. And, yes a lb is an lb.

 

[Seattle_Aquarist]

1 pound of CO2 is 1 pound of CO2 - no matter the phase. At the same temperature and pressure the gas has the same density, so both generate the same volume of gas.

Hi All,

Correct, a pound is a pound.

 

[Sennithgrey]

OP: I'd highly discourage you on attempting this for the many reasons that posters have mentioned and add one more. CO2 is an asphyxiant and is denser than air; If you are venting CO2, that CO2 has to go somewhere and you only need 5%-10% to cause asphyxiation.

 

[Stone454]

There is a youtube vid of a guy filling a sodastream tank with dry ice, I would go that route

 

[Hoppy]

CO2 in any form is pretty cheap. The cost of using CO2 in our aquariums is mostly the cost of the equipment, the regulator, the needle valve, and the storage container (CO2 tank). Liquid CO2, which we buy by having our CO2 tank refilled, is easy to store, safe, and convenient. Solid CO2, which we buy as extremely cold dry ice, in chunks, is not easy to store, not safe to handle, and not convenient. Much worse, there are no commercially available storage containers that trickle out the minute amount of CO2 gas we use per day at a controlled rate and pressure, so we would have to DIY the storage container. Very, very few of us have the knowledge and experience to to that safely.