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. :-)



--
Need Mercedes parts ? - http://parts.mbz.org
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On 2005-01-21, spiral_72 wrote:
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, the problem I can think of, even if you put less in:

CO2 is heavier than air. So if the pressure isn't high enough,
it'll just sit in your bottle and not do anything fun or interesting.

On the other hand, that strikes me as a better idea than winning a
Darwin award, as one poster suggested... ::-)


--
Ross Vandegrift

"The good Christian should beware of mathematicians, and all those who
make empty prophecies. The danger already exists that the mathematicians
have made a covenant with the devil to darken the spirit and to confine
man in the bonds of Hell."
--St. Augustine, De Genesi ad Litteram, Book II, xviii, 37

HA, ha...... go ahead and laugh, Ye' of little faith.

My idea just may revolutionize the aquarium hobby as we know it. Quite
possibly the WORLD!

Anyways....... I bought some dry ice at Publix (a grocery store) for
$1.09 a pound.... Cheap enough I guess. I put about 1 inch of water in
a 20oz coke bottle and 3 pieces of dry ice about the size of a quarter
I suppose......Screwed the top on and um, hehe It went from a coke
bottle shape.... to a um, round kinda shape and all the pleats in the
bottle pulled out.......That is untill it exploded.

So, cool I know it works..... Guess I'll start out small and monitor it
with a pressure gauge.

Oh, yea....... Kids, Don't try that at home......... And if you do.....
leave me a message and tell me that wasn't the most excitement you've
had since breakfast.

In article .com,
spiral_72 wrote:
Anyways....... I bought some dry ice at Publix (a grocery store) for
$1.09 a pound.... Cheap enough I guess. I put about 1 inch of water in
a 20oz coke bottle and 3 pieces of dry ice about the size of a quarter
I suppose......Screwed the top on and um, hehe It went from a coke
bottle shape.... to a um, round kinda shape and all the pleats in the
bottle pulled out.......That is untill it exploded.

Hey if you like that you should try to find the webpage
that has the videos of a guy dropping one pound blcoks
of pure sodium metal into water. That makes a nice bang too
with the added benefit of throwing molten metal and
lye all over the place.

--
Need Mercedes parts ? - http://parts.mbz.org
http://www.mbz.org | Mercedes Mailing lists: http://lists.mbz.org
633CSi 250SE/C 300SD | Killies, killi.net, Crypts, aquaria.net
1970 280SE, 72 280SE | Old wris****ches http://watches.list.mbz.org

(Richard Sexton) wrote in :

In article .com,
spiral_72 wrote:
Anyways....... I bought some dry ice at Publix (a grocery store) for
$1.09 a pound.... Cheap enough I guess. I put about 1 inch of water in
a 20oz coke bottle and 3 pieces of dry ice about the size of a quarter
I suppose......Screwed the top on and um, hehe It went from a coke
bottle shape.... to a um, round kinda shape and all the pleats in the
bottle pulled out.......That is untill it exploded.

Hey if you like that you should try to find the webpage
that has the videos of a guy dropping one pound blcoks
of pure sodium metal into water. That makes a nice bang too
with the added benefit of throwing molten metal and
lye all over the place.


There's one around!??!! Oh man I remember wishing that ever since high
school chemistry class. Our teacher has this huge chunk of sodium (kept
in oil) and he only gave us a tiny chunk to put into a beaker of water
to watch the reaction. I always wanted to get my hands on that chunk
and put it in a swimming pool... or how about a bucket of chlorine. If
sodium reacts that well with H2O I'm sure it would be dandy with CL for
a quick reaction to NACL :P


Actually spiral, I might have a safe (if less exciting) way for your
idea to work. Since all you want to do is have a consistant amount of
CO2 going into your tank, you need a reactor that is consistant but
doesn't build up pressure.

If you have an open bottomed box submerged in your tank with an air hose
from it to your CO2 tank (no valve), the amount of CO2 going into your
tank would depend on the size of the box (the surface area of the open
side). Excess CO2 produced would eventually overflow the box and bubble
up so no explosion risk.

If you find you're not getting enough CO2 dissolving into your tank
water, just get a bigger box which will have a bigger surface area for
the CO2 to react and dissolve into the water. I believe putting it
deeper also works.

Once you have the right size and getting 20-30 ppm of CO2 in your tank,
if you find you're wasting too much CO2 (it's bubbling out of the box)
just insulate the CO2 container more to slow it down.. you should be
able to get a pretty close balance so little CO2 is wasted.

Only problem with this method would be if the CO2 sublimates so quickly,
even with insulation that you waste too much of it.


All that being said, it might be easier and cheaper (unless you get some
free dryice) to go the yeast/sugar DIY co2 method which also has been
known to blow up bottles if that's a must :P

Cheers
P.

"Pete" wrote in message
...
"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.


Hmmm, well I'm not so sure it would work quite like that, but maybe! Vapor
pressure diagrams were a long time ago.

dwhite