# CO2 tank change



## jimmyn (Dec 10, 2010)

I am new to Inj. CO2. I would like to know when its time to fill my tank for the 2nd time. How stable and how long do I have before the pH starts changing. Or do I need 2 tanks so I can change faster.


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## davemonkey (Mar 29, 2008)

I get my tank refilled/exchanged at about 200 psi left in the bottle. You want to make the swap as quickly as possible, definitely in the same day, if you want to avoid any big changes. It's good to have a 2nd tank on hand, but not completely necessary. 

Make sure that you get refilled/exchanged at a place that fills with liquid CO2, not with tank-to-tank pressure refills. They should actually weigh the container and fill with the appropriate pounds of liquid (a 5lb tank should be filled with 4.5 to 5 pounds of liquid CO2, etc...not with 500psi gaseous CO2).


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## Jim Miller (Feb 3, 2003)

At 400psi you have used up all but 5% of the CO2. If it costs you $20 to fill the tank you've wasted only $1. By going down to 200psi you save $0.50 of that. Hardly seems worth killing fish on an end-of-tank dump for a dollar much less $0.50.

IMO

Jim


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## bosmahe1 (May 14, 2005)

It wouldn't hurt to leave the lights off for the day maybe, two that it might take to get the tank filled. That way you don't have to worry about algae issues.


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## jimmyn (Dec 10, 2010)

Thanks this is what I need to know.


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## davemonkey (Mar 29, 2008)

Jim Miller said:


> At 400psi you have used up all but 5% of the CO2. If it costs you $20 to fill the tank you've wasted only $1. By going down to 200psi you save $0.50 of that. Hardly seems worth killing fish on an end-of-tank dump for a dollar much less $0.50.
> 
> IMO
> 
> Jim


Yes, I agree with this. I forgot to mention that I use a 2-stage regulator, so I don't get the dump-off. Sorry about that. But if you use a single-stage, the extra caution is well worth the extra $1.


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## Jim Miller (Feb 3, 2003)

Hi Dave

I mentioned it because few PB setup appear to have DS regs. 

Jim


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## jimmyn (Dec 10, 2010)

Jim what is PB setup


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## Jim Miller (Feb 3, 2003)

Paintball. I was probably confusing threads. 

Jim


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## Dave-H (Oct 5, 2010)

So is there a rule of thumb on what PSI to look for before you go to refill the CO2?

I've heard 600, 400, and someone told me to let it empty completely  I do understand how pressurized gas can give counter-intuitive readings on the pressure gauge so letting go from 400 to 100 probably isn't worth the risk for just a few cents.

But, what IS the right PSI to refill?


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## Jim Miller (Feb 3, 2003)

There is no one right answer. If you have a DS reg your probably safe regardless. For SS I would refill once it started below 800. 

The bux are nits. 

Jim


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## bosmahe1 (May 14, 2005)

When I used to use a single stage regulator with Paintball cylinders, when the high side (cylinder pressure) pressure gauge would start to decrease, the low side or output pressure gauge would start to increase. If you notice the tank pressure dropping and the output pressure increasing, that would probably be a good indicater that it's time to swap or refill the co2 cylinder.

I use a dual stage regulator on paintball cylinders, so now I can run them empty if feel like it. I make it point to a spare handy anyway.


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