A bad day with CO2...

[greatbarrier52]

Just thought I should post this.

by Mike Bateman <vandi-at-well.com>
Date: Thu, 1 Feb 1996
I just had an interesting experience with CO2 this week.

I came home one evening to find all six cats acting very odd. Freaked
out is a better word. None of them would enter the living room. I
didn't think anything about it. Sometimes one of them gets a wild hair
and decides to terrorize the house.

Later that night I opened up the aquarium cabinet to top off the water
in the sump and I noticed a plastic cup, that I keep in the stand to
hold waste test water, was tipped over. Luckily there was nothing in it
at the time but I thought that was odd. At first I figured one of the
cats had learned to open the door to the cabinet. Nah.

I had just had a spare 5 pound CO2 cylinder filled earlier that day and
had stuck it under the aquarium. It was cold and covered in frozen soap
water (the guys check it for leaks everytime I get it filled). I looked
and there was a huge puddle of water under the cylinder. I thought that
was odd. A newly filled cylinder generally sweats but not THAT bad. I
proceded to wipe up the mess and lifted the cylinder out to wipe under
it and noticed the cylinder didn't weigh anything. IT WAS EMPTY!

Suddenly the mystery of the puddle of water AND the freaked out cats was
solved. The 5 pound cylinder had blown its safety valve while I was out.
I figured it must have been pretty loud.

Well I took the cylinder back to the shop and they replaced the safety
valve, which I was suprised to find was only a metal membrane calibrated
to give at 2000psi. They must have overfilled the tank. All they do is
set the cylinder on a big scale, zero it, and fill it to 5 pounds with a
little extra to account for the weight of the hose. It's all very
scientific. :/

I brought the CO2 tank home. It was time to do a little maintenance on
the aquarium anyway so I sat the CO2 tank off to the side and proceded
to work on the aquarium. I was just about done and was cleaning up my
mess when my life flashed before my eyes! The loudest most frightening
sound suddenly sent every cat on a light-speed dash to the basement and
sent my heart pounding out of my chest. It took about 2 or 3 seconds
for me to regain my composure and to realize what had happened. The CO2
tank was lying on its side hissing up an eardrum peircing storm. The
safety valve had blown again, only this time only inches away from me!

Needless to say it took a good hour for my adrenaline levels to
normalize. It took a little longer for the cats to calm down. They
were all discussing new living accomodations.

It only took about 45 seconds for 5 pounds of liquid CO2 to escape into
the air. There was a nice white frozen spot on the carpet. I didn't
think too much about the additional CO2 in the air as I didn't notice
anything such as increased resperation or light headedness. There was
plenty of O2 in the air. I'm sure the house plants LOVED it. :)

A casual glimps at my pH controller revealed something odd though. My
tank pH had dropped four tenths of a point! I checked the other
aquarium and it also had dropped an equivalent amount. The additional
CO2 in the air had caused the aquarium pH to drop! It took over an hour
for the pH to even start dropping! It was probably 3 hours before the
pH in the 45g tank returned to normal. The 75g has a trickle filter so
the pH returned to normal a little more quickly.

I returned the 5# cylinder and they again replaced the safety valve.
This time I had them skip adding that "little extra". I immediately
pulled the 10# cylinder off and placed the regulator on the 5# so that I
could actually SEE the pressure in the tank. It was only 500psi. As
the cylinder warmed the pressure rose but stopped at 900psi. Whew...

So BE CAREFUL out there folks! I've had these things refilled several
times and this was the first time this has happened. I hope it'll be
the last!

Oh, I didn't mention that the safety valve had been pointing towards a
large palm plant when it blew. It blew about a 3" of soil out of the
pot. That soil covered EVERYTHING within a 12ft radius. Boy, did I
have a big mess to clean up. :)

Mike

[dan]

makes you think twice about co2. i have a 20 pounder setting in my fish room. hope it behaves itself. yours was a 5 pounder i'd hate to here what a 20 pounder sounds like. you still need to come by!

[matt]

Yep, extra CO2 in a room can easily cause ph issues in your aquarium. This is a real problem with people that have tightly sealed houses, and/or lots of heavy breathers.

At Natwells in S.A., the guy just grabs your tank, hooks it up, opens the valve, waits a few seconds, closes the valve. Then "checks" the weight by picking up the tank and hefting it for a second, then hands it back. Real high tech and accurate. I once made the mistake of asking him about this and was treated to a sarcastic rant in Spanglish.

[JesterGrin_1]

Lol Spanglish Matt you Kill me lol. But if you go to Natwell give it to the older guy by the name of Joe. When you fill the tank there you do open the valve to empty the bottle since you fill the bottle by weight. Once it is empty then they put it on the scale with the filler hose on and zero out the scale then fill till just about the size of the bottle will hold. Say a 5 pound or 10pound or 20pound. Now the 5 pound bottles are a little more tricky because they weight so little. I would stick with atleast a 10pounder. In the summer they or should put a little less CO2 in the tank to compensate for expansion for the higher temps. You aught to see a 800pound CO2 tank pop a valve lol. If you have questions like these I would be glad to answere them. I used to work there and the only people you can trust as to know what they are doing is Joe and Isac. I was the Nitrogen Man lol. I handled those Big White tanks next to telephone poles you see now and then. Try moving a tank of 600 to 800 pounds by hand :). But since I left now they deliver the tanks empty and go by with a trailor and fill them. :)

[Tim Marvin]

Well duh! Of course if you compress gas into a cylinder and then put it in a hot place, (garage, under tank, in the sun in the back of the truck), the temp will raise even more and burst the expansion cap. That plug is there to save you life! He should be thankful it popped and didn't burst the tank. That would have been a mess to clean up if the tank blew next to him....... Anyway these bottles are safest placed outside of the stand in good air circulation in a cool room. I am surprise the burst cap was so low.. Scuba tanks are filled to 3000psi and the caps blow at or around 4000. Imagine a cap holding on one of those tanks and it blowing on your back...LOL..... The sharks would really love that! Not to mention your buddy gets a front row seat at the feeding frenzy.... Of course after you jump into the cooler water that is about a billion to one chance of that ever happening considering they are hydro tested every five years....
Good info to know though.. Thanks for the article, I think I'd have a little more than dirt to clean up. Laundry would probably be first.