# CO2 Cylinder Pressure Dropping



## NyteBlade (Aug 19, 2006)

For all of you CO2 cylinder experts out there, I have a 5# CO2 tank with a JBJ regulator.

I bought the CO2 cylinder a few years ago and a JBJ regulator. I used the Co2 cylinder in my 29 gallon for probably 4 or 5 months @ 2bps. Just recently I took off the cylinder and the regulator, and installed one of those dual manifolds that fits directly into the regulator.

That's been probably about 1 1/2 months ago. Since then, I've been running it on a 29 gallon and a 20 gallon, both at 3 bps. Last week I looked and the PSI was down to 500 (it usually hovered at about 1200). Knowing the thing was most likely exhausted, I cut back all the needle valves and unplugged the solenoid.

Since last week, pressure has dropped to about 250 PSI. Somehow I've lost 250 PSI in the last week without the thing being on. I think with 5 months @ 2bps, and a month at 6 bps, the 5# CO2 cylinder was probably due to expire. The thing I'm worried about is the drop in pressure. I assume the CO2 tank was hosed anyway and needs to be refilled, but should a near-empty CO2 tank continue to lose pressure?

The only thing I've tinkered with is the solenoid and the manifold. I don't think it's possible to lose CO2 via the physical solenoid. I sprayed some windex around the manifold. Besides washing some residual pipe goo, I don't see much in the way of air bubbles.

Is my best option just to get the thing refilled and see how long it lasts?
How long _should_ a 5# CO2 tank last at 6 bps?


----------



## epicfish (Sep 11, 2006)

Yes, it's possible to lose CO2 via the regulator if there are leaks in the needle valve and/or solenoid connections anywhere. Temperature changes can also affect your CO2 pressure readings, and with a nearly empty tank, even minor temperature fluctuations can affect the pressure readings. 

If it's been a few years, the cylinder may also be due for a hydrotest which makes sure that the CO2 cylinder + valve themselves aren't leaking. 

If you can find a place to swap, and provided you want to swap your tank out, that might be the least expensive option (save $20 or so for a hydrotest).


----------



## NyteBlade (Aug 19, 2006)

epicfish said:


> Yes, it's possible to lose CO2 via the regulator if there are leaks in the needle valve and/or solenoid connections anywhere. Temperature changes can also affect your CO2 pressure readings, and with a nearly empty tank, even minor temperature fluctuations can affect the pressure readings.
> 
> If it's been a few years, the cylinder may also be due for a hydrotest which makes sure that the CO2 cylinder + valve themselves aren't leaking.
> 
> If you can find a place to swap, and provided you want to swap your tank out, that might be the least expensive option (save $20 or so for a hydrotest).


Thanks epicfish  I'm going to call the 2 CO2 places around here and talk to them tommorow. I want to see if I can trade the 5# in for a 10# without much expense or hassle. Who knows, not too sure how anal they are about that.

How tight should the solenoid be against the regulator? It's attached to the bottom via a nut. The electrical part wiggles around quite a bit. 

The Windex test didn't yield any immediate hits. I'll have to try again. I'll tighten up everything on the regulator solenoid-wise. I might just be being paranoid, but better to be paranoid than to go through a 5 or 10# CO2 tank in a week


----------



## Mishmosh (Nov 27, 2003)

*me too*

Same thing happened to me recently. I normally get 6 months out of my 10lb cylinder, but after 6 weeks after my last fill, I noticed about 500psi and about 200psi a week after that. I refilled it and am keeping a closer eye on my useage--I find it hard to count bubbles and maybe I was overdoing it.


----------



## epicfish (Sep 11, 2006)

NyteBlade said:


> How tight should the solenoid be against the regulator? It's attached to the bottom via a nut. The electrical part wiggles around quite a bit.


My solenoid is actually pretty secure to the regulator. You can tighten up the nut some with a wrench. Don't over-do it! 



Mishmosh said:


> Same thing happened to me recently. I normally get 6 months out of my 10lb cylinder, but after 6 weeks after my last fill, I noticed about 500psi and about 200psi a week after that. I refilled it and am keeping a closer eye on my useage--I find it hard to count bubbles and maybe I was overdoing it.


There's no way a high bubble rate could empty a 10# tank that fast. You have a leak. Check the joints with soapy water.


----------



## OverStocked (May 26, 2007)

In my experience once you start to see a drop in pressure it happens very quickly. It should be right around 800 till there is no liquid left, and then it will drop when it is only gas left. Once it is down to "fumes" it will go faster than you would expect.


----------



## aquatic-store.com (May 24, 2003)

You can try a solution of a small amout of water and detergent for bubbles and see your leak wherever it is coming from

Marc


----------



## NyteBlade (Aug 19, 2006)

over_stocked said:


> In my experience once you start to see a drop in pressure it happens very quickly. It should be right around 800 till there is no liquid left, and then it will drop when it is only gas left. Once it is down to "fumes" it will go faster than you would expect.


I guess my major concern was it seemed like it was losing pressure even while the thing was turned off. I don't recall how much it was down to originally. I swore it was 500, then I shut it off, then it went down to 250. Who knows, I could've misread it, maybe it just took the gauge some time to adjust. I'll keep a close eye for leaks though.

In other news, the CO2 place said I could upgrade from a 5# to 10# for a mere $25. :thumbsup:


----------



## NyteBlade (Aug 19, 2006)

Looks like I'll have to chalk up a win to epicfish for the temperature variation thing and the hydrotest idea.

Just exchanged my 5# for a 10#.

It was $25+8 for a hydrotest and a fill for my 5#

It was $25+9 to upgrade to a nice shiny 10# tank with CO2 included. Needless to say, the 10# fit underneath my tank and I get double the CO2 :thumbsup: Lifting the thing to my car coming off of wrist surgery 4 weeks ago probably wasn't the brightest idea.

A brand new 10 lb. cylinder is showing 900 psi, without any apparent leakage. During the summer it showed close to 1200 psi, so I guess the cool days and the tank being in the basement must be playing havoc with the pressure.


----------



## epicfish (Sep 11, 2006)

Glad to hear you got a nice shiny tank. Probably aluminum too!


----------



## NyteBlade (Aug 19, 2006)

epicfish said:


> Glad to hear you got a nice shiny tank. Probably aluminum too!


Thanks epic. Well, the 5# one was really shiny, I think that one was aluminum. The 10# I'm pretty sure is steel. It's kind of a dull, painted gray, but it looks nearly brand new for a steel tank. I'm guessing besides the rust issue, a steel tank isn't a huge downside. I'm just glad they didn't make me hydro test the alumnium tank. The test date was '03 :icon_eek:

The one plus about aquariums is usually when I go to swap it out, I just tell them it's for an aquarium and try to "coerce" them into giving me the shiniest tank available :thumbsup:


----------

