# [Wet Thumb Forum]-Could my CO2 be contaminated?



## Jeremy S (Apr 9, 2006)

About two days after I exchanged my empty 10 lb CO2 cylinder for a new one three of my dwarf neon rainbow fish died and ever since then about every couple of weeks a fish gets sick for no reason and dies. It’s been about two months now and I have tested the water for every thing that I can think of but it’s all fine. The pH only changes from about 7.0 in the morning to about 7.1 / 7.2 in the evening. The temp stays around 79 F. and the ammonia, nitrite, nitrate and phosphate are all at the levels they should be. The only thing I can think of now is that the new CO2 has something in it. Could it be possible? I got it at the same local welding shop as the other one.


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## Jeremy S (Apr 9, 2006)

About two days after I exchanged my empty 10 lb CO2 cylinder for a new one three of my dwarf neon rainbow fish died and ever since then about every couple of weeks a fish gets sick for no reason and dies. It’s been about two months now and I have tested the water for every thing that I can think of but it’s all fine. The pH only changes from about 7.0 in the morning to about 7.1 / 7.2 in the evening. The temp stays around 79 F. and the ammonia, nitrite, nitrate and phosphate are all at the levels they should be. The only thing I can think of now is that the new CO2 has something in it. Could it be possible? I got it at the same local welding shop as the other one.


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## Justin Fournier (Jan 27, 2004)

I am not sure of the chance of it being contaminated, but it is possible. I know C02 can come in different qualities, as in the % of false gasses in it. I am not sure if the quality from say a welding application vs a fire extinguisher application is any different. I suppose it is possible that a false gas in poor quality C02 could be less then benefitial for your tanks inhabitants, but be of no relevance to the application in which it was intended, say welding.


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## Rex Grigg (Jan 22, 2004)

I really can't think of any other gas contamination that would cause the problems you are having. But then again I NEVER exchange my cylinder. I guess it's possible that something has gotten into the tank and is making it's way into the water.

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## Jeremy S (Apr 9, 2006)

Should I try to get another cylinder from a beverage company?


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## Rex Grigg (Jan 22, 2004)

That would be the easy solution.

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## Justin Fournier (Jan 27, 2004)

Beverage comapnies around me are never able to fill a bottle on the spot (I never trade my canister in 5lbs. Aluminum new). So I go to the fire supply place. They can do it on the spot, the quality is top notch and the price is right!


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## Jeremy S (Apr 9, 2006)

Another one of my fish is starting to get sick. Should I turn off the CO2 until I can get a new cylinder tomorrow? Would that make the pH go up enough to stress out the fish?


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## Rex Grigg (Jan 22, 2004)

What kind of symptoms are you noticing? Have you checked the CO2 level in the tank?

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## Jeremy S (Apr 9, 2006)

I keep the CO2 around 15 ppm. The fish usually just start clamping their fins and won't eat. And then eventually they die.







The only thing I can think of is the CO2.


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## gsmollin (Feb 3, 2003)

That doesn't sound like a "poison gas" scenario. It sounds like a contagious infection that is making the rounds. A "poison gas" should pretty much be affecting all fish of the same species at the same time.

That being the case, you should be taking steps to stem an infection as well as shutting off the CO2.


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## Jeremy S (Apr 9, 2006)

Why should I shut off the co2 if it’s just a contagious infection? How can I stop the infection since the water is just fine i.e. ammonia 0, nitrite 0… I don’t want to add meds because of the plants and the healthy fish.


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## Jeremy S (Apr 9, 2006)

I just called the welding supply store and they said that all the CO2 they sold was beverage grade so it would be impossible for it to be contaminated. The only contamination problems they have had are from water getting into the cylinders. Do you think to cylinder could of rusted from that since its kind of old. I also noticed that they had replaced the valve on top so maybe something got into the cylinder when they were doing that.


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## Rex Grigg (Jan 22, 2004)

It's not your CO2. Rust in the tank is not going to cause any toxic reactions in the tank. If they are using beverage grade CO2 the gas is good. Anything that could have gotten into the cylinder is not going to cause a problem. If it was contaminated CO2 then all your fish would have died within a short time of each other. You need to look else where. And an infection is not going to show up in water tests. You need to find out what is killing the fish and treat it. Don't use a shotgun approach. Are there any other symptoms besides clamped fins?

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## EDGE (Feb 28, 2004)

you know.. I had a problem like this way before I added co2. one fish would die after another. Then all of a sudden, poof they stop dying. I lost all my rainbows like this. Funny thing is, I don't remember it killing any other fish beside rainbows.

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## ranchwest (Jul 17, 2005)

It probably isn't the gas, but....

most beverage companies only sell CO2. Welding supply companies usually sell other gases, such as argon. If they put C02 into a tank that previously had argon (and probably some still in there), who knows?


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## gsmollin (Feb 3, 2003)

That's pretty unlikely. Assuming it did happen, argon is an inert gas, and will not make the fish sick. It would just bubble to the surface.


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## Jeremy S (Apr 9, 2006)

I exchanged the cylinder for another one about 10 days ago. The guy at the welding shop did it for free and he got the newest looking one. The fish are doing allot better now. They are more active and the two that looked like they where starting to get sick right before I exchanged the cylinder are doing great.







I noticed that when I took off the regulator on the old cylinder there where little pieces of metal and other small objects on the washer.







It was probably contaminated somehow. At least the fish are doing better now.


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