# A differnece in Co2 we buy when we refill and does it matter?



## maknwar (Aug 10, 2008)

I think the only difference is purity. And for our use, there isn't a difference.


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## proaudio55 (Oct 20, 2011)

LOL!! "Medical grade" CO2? That sounds like a marketing gimmick to me. Carbon Dioxide is toxic above a few percent.

With "pure" industrial gasses, they typically run about 99.9%. The laboratory grade stuff is more like 99.999 or 99.9999 and used with certain lasers and some other niche applications. Is .001% or 0.0001% really worth paying 2-4 times as much for? Not in my world.

A few PPM's of trace oxygen, nitrogen, or VOC's is not going to hurt the critters.

Thinking about it, with UHP (ultra high purity) you need special cylinders for it and special regulators that won't contaminate the gas. Short story long, the cheap-o CO2 that welding shops sell is plenty good!


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## dasob85 (Feb 4, 2012)

I would think the people at airgas would be less likely to screw up refilling as opposed to the paintball place if you go to ie dick's or sports authority. although having said that, 18-25 seems kind of high for a 5lb tank.


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## J1Time (Apr 12, 2012)

> LOL!! "Medical grade" CO2? That sounds like a marketing gimmick to me. Carbon Dioxide is toxic above a few percent.


Pretty sure this is what is used for laproscopic surgery


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## jjp2 (May 24, 2008)

the Airgas in my air is at $38 for a 20lb tank, so I can see the $18 to $25 range on a 5lber.


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## Naekuh (Oct 19, 2011)

WOW u guys are paying a lot to get a tank filled.

I paid 20 dollars + free washer for my 20lber with beverage grade Co2.


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## proaudio55 (Oct 20, 2011)

J1Time said:


> Pretty sure this is what is used for laproscopic surgery


Well I stand corrected! I had no idea they inflated people like a balloon with CO2 to do surgery. But still, back to the OP, using high purity seems unnecessary in a planted tank.


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## AaronT (Apr 11, 2004)

There is such thing as medical grade, but not all Airgas stores have it. They actually won't sell you the medical grade without an order from a doctor so it's a moot point. 

In short, you're probably just fine using the stuff from the paintball store.


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## jreich (Feb 11, 2009)

co2 is co2, there is absolutley no dif between food grade and industrial, and like said before no reason to sping for the medical quality is you could even get your hands on it.


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## samamorgan (Dec 31, 2011)

jreich said:


> co2 is co2, there is absolutley no dif between food grade and industrial, and like said before no reason to sping for the medical quality is you could even get your hands on it.


Co2 is not just co2. It is co2 + whatever else has gotten into the bottle. I assume medical grade co2 would have a very high purity for laproscopic surgery. It has to be more pure so that you aren't injecting potentially harmful gasses, chemicals, or debris into the human body.

They use Co2 to inflate people because they use a tool that cauterizes when they cut and co2 isn't flammable. If they pumped someone full of anything else the person could explode when the cauterization was taking place. Bad mojo.

I know all of this because i had my gall bladder taken out last year. Actually wasn't a bad experience, in and out of the hospital in a few hours, week of recovery, no more horrible abdominal pain.


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## Seattle_Aquarist (Jun 15, 2008)

Hi Aquaticfan,

Basically CO2 is CO2 although some may be 'cleaner' than others it is all the same to my plants. I found that Fire Extinguisher dealers can fill CO2 tanks as well; I get my 15# tank filled for $15. I weigh it empty then I weigh it full, it should weigh 15# more when full than it was empty.

Many paintball filling stations don't completely fill my tank, sometimes I get 7# or less. Needless to say it is not a bargain, especially when I have to run out and fill my cylinder twice as often.


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## mordalphus (Jun 23, 2010)

I use airgas because it's a 2 minute drive from my house. The nearest paintball store is a 20 minute drive, and they only fill hobby tanks (the 20 ounce tanks). The nearest welding supply is just down the street from the paintball shop, and is open 9-5 m-f, which happens to be when I'm at work. I pay 15-20 dollars for a 5 lb tank to be filled every 3 months, saving a few dollars isn't something I'm worried about, especially when I have to go so far out of my way, or take time off of work to do it.


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## jreich (Feb 11, 2009)

samamorgan said:


> Co2 is not just co2. It is co2 + whatever else has gotten into the bottle. I assume medical grade co2 would have a very high purity for laproscopic surgery. It has to be more pure so that you aren't injecting potentially harmful gasses, chemicals, or debris into the human body.
> 
> They use Co2 to inflate people because they use a tool that cauterizes when they cut and co2 isn't flammable. If they pumped someone full of anything else the person could explode when the cauterization was taking place. Bad mojo.
> 
> I know all of this because i had my gall bladder taken out last year. Actually wasn't a bad experience, in and out of the hospital in a few hours, week of recovery, no more horrible abdominal pain.


for our purpose co2 is co2, were not doctors here, were growing weeds underwater, and like i said you probably cant even get your hands on medical co2, and if you could why would you even want to bother unless it was free.
the point i was trying to make was some stores have 2 grades of co2, food grade and industrial... They will try to trick you into buying the "better stuff" when in fact they are both exactly the same thing.


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## samamorgan (Dec 31, 2011)

Yes of course you are right. I was just trying to illustrate the difference for educational purposes, you never know when the wrong assumption will come back and bite you later in life.


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## kevmo911 (Sep 24, 2010)

It's been said by a couple people, but I'll put in my two cents - for our purposes, CO2 is CO2. Even if there is a small amount of "other" gas in the (relatively) low-grade industrial CO2 we get, and even if that small percentage were toxic (it's not), it would gas out of the tank too quickly to make a difference to any living organisms in the tank. And we're talking about a fraction of a percent here, just to help clarify.

So, buy your low grade or high purity CO2, and it won't make a difference. Just find the cheapest place around. And remember, it's generally cheaper to swap than to refill. And there are more places that swap, rather than refill.

I have one nice 20# aluminum cylinder, and two steel 5# cylinders. I swap out the 5's for $12 or so each, and I refill the 20# at a place right down the street from work. It's a bit more expensive ($24), but it's convenient, and I'll only have to do it once or twice a year. And they're all industrial-grade CO2, as far as I know.


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