This one seems to cause some very negative comments.
 

Alright, I've got this idea. Boy, that sounds like the beginning to an
end.

I figure I can drop dry ice in a tank, cap it with a regulator and have
CO2 for some period of time for my planted aquarium. Obviously it will
require more than a handful of dry ice and chances are it ain't quite
that simple. Right now I am building a tank with a mouth wide enough to
accept an entire piece. I figger I'll pack the stuff in there like the
old shotgun wadding with a length of 2x2 or something until it's full,
and cap it.

I run a search on this over the web and the Google groups. I got the
same response: "DON'T DO IT, IT'S TOO COMPLICATED"

What's up with dat? Any particular reason? I don't want to hear that
the stuff is not sanitary either. The air in my house probly ain't
sanitary after a nice homemade bowl of chille. Heck, it's free......
They pack ice cream in it at the gas station (they sell ice cream in
cones) and they just throw it away.

"spiral_72" wrote in news:1106256969.936458.265300
@c13g2000cwb.googlegroups.com:

Alright, I've got this idea. Boy, that sounds like the beginning to an
end.

I figure I can drop dry ice in a tank, cap it with a regulator and have
CO2 for some period of time for my planted aquarium. Obviously it will
require more than a handful of dry ice and chances are it ain't quite
that simple. Right now I am building a tank with a mouth wide enough to
accept an entire piece. I figger I'll pack the stuff in there like the
old shotgun wadding with a length of 2x2 or something until it's full,
and cap it.

I run a search on this over the web and the Google groups. I got the
same response: "DON'T DO IT, IT'S TOO COMPLICATED"

What's up with dat? Any particular reason? I don't want to hear that
the stuff is not sanitary either. The air in my house probly ain't
sanitary after a nice homemade bowl of chille. Heck, it's free......
They pack ice cream in it at the gas station (they sell ice cream in
cones) and they just throw it away.



Actually sounds like fun but a few of the things I can think of off hand.

1. I'm not sure if you'll get enough pressure to run a regulator. I've
heard many horror stories of regulators allowing CO2 dumps into tanks
because they let their CO2 tank get too low and thus not enough pressure
for the regulator to work with, the remaining CO2 gets injected overnight
and game over.

2. If you do get enough pressure for a regulator, how good are you at
building high pressure tanks? I don't think you want any sort of explosion
near a large glass tank filled with water.

3. If you rely on the speed of it melting to dictate the injection rate
(maybe a setup with a insulated box for the ice and an air tube to the
intake of a canister filter) then it's an issue of controling the speed.
You could change that with using more or less insulation and I could see
that maybe working.. no worse that yeast and sugar for varing rates.

P.

"spiral_72" wrote in news:1106256969.936458.265300

3. If you rely on the speed of it melting to dictate the injection rate


Just a nitpick, but CO2 sublimes instead of melts.

dwhite

"Dan White" wrote in news:0t%Hd.571$vo6.564
@fe11.lga:

"spiral_72" wrote in news:1106256969.936458.265300

3. If you rely on the speed of it melting to dictate the injection rate


Just a nitpick, but CO2 sublimes instead of melts.

dwhite




ROTFLMAO. Oh man I know, I'm a science geek I do that nitpicking stuff
myself. I just didn't think it was worth it having people look up the
definition of sublimation :P

P.

"Pete" wrote in message
...
"Dan White" wrote in news:0t%Hd.571$vo6.564
@fe11.lga:

"spiral_72" wrote in
news:1106256969.936458.265300

3. If you rely on the speed of it melting to dictate the injection rate


Just a nitpick, but CO2 sublimes instead of melts.

dwhite




ROTFLMAO. Oh man I know, I'm a science geek I do that nitpicking stuff
myself. I just didn't think it was worth it having people look up the
definition of sublimation :P

P.

Like they say, "Damned if you do, damned if you don't." :)

dwhite

What I am hoping:

The dry ice will sublimate inside the tank, building pressure. At some
point the pressure will be high enough inside the tank that this
process stops (untill you leak a little CO2 into the aquarium.

At what pressure does the CO2 reach this.......equilibrium? I have no
idea...... What's worse I don't know how to find out other than
experiment. So, with this in mind (don't laugh) I found some 6" OD,
1/4" wall seamless steel tube to which I am going to tig weld 1/4"
thick plate "plugs" to cap the tank. I Already have the round stock and
I have turned the caps on a lathe.......O.K. now you can laugh.

The tank weighs about 15lbs! and I figger it'l be good to about
Mmmmmmmm........275,000psi. In all seriousness, I'm not worried about
the weld till at least 1500psi. Irregardless, the first time I am going
to pressurize this "bomb" in the front yard.

What's really gonna suck, is if the CO2 sublimates to 15psi....at which
point it reaches this "equilibrium" and I now have a very interesting
looking boat anchor. I guess lucky enough for me I pulled all this
stuff out of the dumpster at work. So, so far it hasn't cost any money.

Hey, this might even draw a crowd! Maybe, I could charge
admission!!.............Maybe, not.

Well, if I figured this right:

P = n * R * T / V Whe

P = pressure in atm
n = amount of substance in moles
R = Thermal expansion ( 1atm / K*mol )
T = Temp change in Kelvins
V = Volume of a sealed container in Liters

( n ) for CO2 is 22.727mol
( R ) for CO2 is 0.08206
( T ) is 298K
( V ) is 6.81322 Liters

Ignoring the air present in the container when it was sealed, and
introducing 1 Kg (2.2lbs) of dry ice in my 6.813 L tank, while the air
in my living room is 24 C (75 F)
final pressure inside the tank will be 8238.7 psi.

Oh, crap.

"Dan White" wrote in
:

"Pete" wrote in message
...
"Dan White" wrote in news:0t%Hd.571$vo6.564
@fe11.lga:

"spiral_72" wrote in
news:1106256969.936458.265300

3. If you rely on the speed of it melting to dictate the injection
rate


Just a nitpick, but CO2 sublimes instead of melts.

dwhite




ROTFLMAO. Oh man I know, I'm a science geek I do that nitpicking
stuff myself. I just didn't think it was worth it having people look
up the definition of sublimation :P

P.

Like they say, "Damned if you do, damned if you don't." :)

dwhite



Hey, just thought of something. CO2 in a pressured tank is in liquid form.
So if he puts this dry ice in a sealed tank that does get a high enough
pressure once enough CO2 has sublimated, as the rest of the CO2 thaws it
will turn into a liquid instead of a gas... so it would 'melt'. hehe.

P.

"spiral_72" wrote in news:1106326353.925305.265280
@z14g2000cwz.googlegroups.com:

Well, if I figured this right:

P = n * R * T / V Whe

P = pressure in atm
n = amount of substance in moles
R = Thermal expansion ( 1atm / K*mol )
T = Temp change in Kelvins
V = Volume of a sealed container in Liters

( n ) for CO2 is 22.727mol
( R ) for CO2 is 0.08206
( T ) is 298K
( V ) is 6.81322 Liters

Ignoring the air present in the container when it was sealed, and
introducing 1 Kg (2.2lbs) of dry ice in my 6.813 L tank, while the air
in my living room is 24 C (75 F)
final pressure inside the tank will be 8238.7 psi.

Oh, crap.



Well look on the bright side, if your tank doesn't hold, your manner of
death will be posted on the next list of the Darwin Awards :P

P.

Oh, crap.

Now you know why you haven't heard of this before. :-)



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