Hi,
My CO2 tank guage was in the red this weekend, telling me to order more. So I removed it and took it outside and released what was left, which seemed to be a lot. With the valve fully open it went for almost a minute. (5lb tank)

How long do people tend to let their tanks run in "the red" before they get it re-filled?

when I notice my valve in the red zone (i only check like once a week)
I try to get it refilled within that week (whenever I'm free)...

I got a 10lb.

I have a 26lb bottle, think its going to be a long time till I need to check mine

I've read somewhere that if you run a tank near empty it can dump too much CO2 into the water. I certainly don't know this for a fact as I've only just started using my cylinder.

Ian

Yeah well, we don't really want to go there again...

If you have a needle valve then it's okay to run the CO2 tank empty. What will happen is that there will be a small rise in the output pressure which will increase the bubble rate slightly. Unless the KH is borderline or you are running the tank at absolute maximum CO2, the increase won't be noticeable.

I have my CO2 line inserted into a submersible pump and can hear a little whoosh each time a bubble hits. Last night I heard no woosh, and sure enough the CO2 tank is empty. I never even noticed it until it was quiet. I've run CO2 tanks empty for years with no ill effect, as long as there is a needle valve to control the outflow.

TW

I took my tank in to be filled today and the guy told me that there would likely be about a 1/5 tank left when the guage indicated "time to refill".

My small pressurised ran out recently. Very little notice, a few days, but just fizzled out. It has a needle valve.
Martin

Thanks. That's good to know. Next time my tank goes into the red I won't panic. I do have a needle valve on it so I'll let it run quite a bit longer now.

I let me 20lb go to empty, but then, it was the weekend and I couldn't get a refill until Monday. I have an empty 10lb; I think I'll be refilling this one as well as an emergency backup.

A friend of mine works at a welding store where I get mine re-filled and he says that the red zone (re-fill) is indicated because that is where there is no more “liquid” CO2 in the tank. Yes there is pressure but not as concentrated as pure CO2. The pressure fall off is also faster below 400 psi.