# [Wet Thumb Forum]-5 lbs Cylinder life?



## Mike K (Mar 27, 2003)

How long should a 5 lbs CO2 cylinder last? What is the PSI on a close to emptying CO2 cylinder? my bubble rate is about 5bps. Thanks

Mike K.


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## Mike K (Mar 27, 2003)

How long should a 5 lbs CO2 cylinder last? What is the PSI on a close to emptying CO2 cylinder? my bubble rate is about 5bps. Thanks

Mike K.


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## Rex Grigg (Jan 22, 2004)

The cylinder should last for years and years, depending on how often you fill it. The gas inside however will last a finite amount of time. There is not hard and fast rule or way to tell how long a tank will last at any bubble rate. A normal CO2 tank at at 70 degrees will show a tank pressure of 800 psi. Once it drops below 600 psi all the liquid CO2 is gone. However the best thing to do is weigh the tank. Stamped on it should be the Tare Weight (TW). If the tank has a TW of 12 lbs and you weigh the tank and it weighs under 13.5 lbs you should start thinking about getting it fixed. If you have a good needle valve and regulator setup you can run a tank to a very low pressure, under 100 psi, without too many problems.

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## BobAlston (Jan 23, 2004)

I would guess about 6 weeks or so, based on comparison of how long mine lasts and our relative bubble rates.

Bob


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## Tenor1 (Mar 3, 2003)

Are you sure the bubble rate is 5 bubbles per second? I don't even know if it's possible to see that fast movement. I was told to measure the number of bubbles in a 10-second period. I really counted bubbles for the first few months getting acquainted with using a presurized system. The next few months I carefully calculated pH and KH measurements without counting the bubbles.

Now I look at fish reactions and pearling. My albino corys hang out at the top of the tank when the pH gets below 6.8 and thin-leaved plants pearl a lot at 6.8. It took several months to achieve a comfort level before I stopped taking daily pH levels. 

On my 36-gallon tank a 5-pound tank lasted 12 months. I use the Eheim single-gauge valve and it dispensed evenly until the very end of the available CO2 without any type of dumping. 

My current practice is to 
1)look daily at the difuser to insure bubbles are visible
2) observe fish and plant behavior
3) make sure the mist leaving the disc is fine enough
4) clean the disc and take a pH reading every 3 weeks.

I was paranoid in the beginning thinking the fish would suffer from an overdose of CO2 and go into pH shock and luckily this never occurred. The fear and mystery of using CO2 gets less with time.

The next hurdle is refilling the tank, lol. There are different grades of CO2, but that is for another topic.

Regards,
Carlos 

==============================
I try to keep the tank plain and simple but it never stays that way


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## Dr V (Feb 5, 2003)

On my 29gal with a bubble rate of about 2 bubbles/sec., a 5 lb. tank lasted 14 months.

I got tired of not having a backup tank when the 5 lb. ran out, so I went out and got a 15 lb. tank. Now I have enough CO2 for years!

Lobos


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## JamesHoftiezer (Feb 2, 2003)

A 5lb tank on a mid sized high-light aquarium should last 6-12 months, but this is very general.

If you run 24x7, faster bubble rates, higher lights will all make a difference.

*James Hoftiezer

Tank Journal - Aquascape ( Latest / Archive )
Tank Journal - Parts and Construction ( Latest / Archive )*


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## Mike K (Mar 27, 2003)

My bps is about 5 and the psi readings on the cyclinder is 450psi. The reading on the CO2 regualtor is 20psi. It is a aquamedic regulator. I think I have about a month left in it. It has been running for about 2 months now on a controller. I did not use the CO2 tubing that Robert gave me b/c the tubing was so small. So I am using black tubing, I bought it at Lowes, don't know what type. How do I test to see it the tubing is leaking CO2?

Mike K.


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## Rex Grigg (Jan 22, 2004)

You have a leak, or at least a very efficient atmosphere CO2 diffusion system. I can't think of too many black tubings they sell at the BORG but if it's the one I think it is then it's very porous to CO2. Trust me on that. You could try submerging the tubing in water and seeing if it leaks, or you could put some soapy water on it and see if it leaks. Or you can go to a home brew shop or maybe a welding shop and they have a fluid that you can paint on it and it will change color if there is a leak.

And I'll bet you have less than a month left with a tank pressure of 450 lbs.

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## gsmollin (Feb 3, 2003)

> quote:
> 
> Originally posted by Mike K:
> How long should a 5 lbs CO2 cylinder last? What is the PSI on a close to emptying CO2 cylinder? my bubble rate is about 5bps. Thanks
> ...


The CO2 in a 5 lb. cylinder should last 9-10 weeks at 5 bubbles/sec.

Your second question requires a lengthy answer. Since I don't type well, go here: http://www.reefscapes.net/articles/breefcase/co2_tanks.html for a lengthy answer. Remember that CO2 is NOT a gas inside the tank, but either a liquid, or a super-critical fluid.


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## JamesHoftiezer (Feb 2, 2003)

If you are truly at 450psi, then all of the liquid CO2 is gone and you only have gas left. You have day(s) instead of weeks.

I would check the tubing and get that tank refilled. I use beverage line tubing from Home Depot. It is clear PVC with a braid visible inside. It is commonly referred to as beverage tubing. Great stuff.

*James Hoftiezer

Tank Journal - Aquascape ( Latest / Archive )
Tank Journal - Parts and Construction ( Latest / Archive )*


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