# co2 cylinder almost empty?



## Darkblade48 (Jan 4, 2008)

When the high pressure side reaches around 100-200 PSI, I would suggest you fill your tank. Since you are using a Milwaukee regulator (and presumably the stock needle valve that comes with the MA957), I would not use the tank until it goes completely empty (i.e. 0 PSI). You would be risking end of tank dump (i.e. around the last 100 PSI or so, all the remaining CO2 just gets emptied into your aquarium; the end result if you're not around, a tank of dead inhabitants, and lots of happy plants). 

Tanks should read ~800 PSI or more when filled. 750 PSI is cheating a little.

I don't think a 5lb tank should empty that fast; given your current rate of usage, you'll go through a 5lb tank in ~3 months, which is unusually fast. I would check your setup for leaks with some soapy water. 

Even turning the gauge on full blast for a few seconds should not empty your CO2 that significantly (unless it happened on more than one occasion...)


----------



## captain_bu (Oct 20, 2007)

Darkblade48 said:


> Tanks should read ~800 PSI or more when filled. 750 PSI is cheating a little.


There is no "should" involved... CO2 tanks are filled by weight not according to the pressure on a gauge (there is no regulator connected to the tank when it is filled, the tank is emptied before they start) ... the PSI will vary depending on the ambient temperature and ultimately the temperature of the tank itself. The room my tank is kept in stays pretty cool for most of the year and with a full tank my gauge hardly ever tops 700 PSI. It usually takes a day after a fill for the temperature of the tank (and the reading on the gauge) to stabilize.

Regardless of what the high pressure gauge reads after a fill though it should stay at that reading until the liquid gas is used up. At that point the pressure will start to drop and generally within a week you need a refill.

I agree that the OPs pressure starting to drop indicates that the tank is starting to run out and one month seems like an awfully short amount of time for that to be happening. I would check carefully for leaks. I have never used a Milwaukee regulator but based on what I have read about them the advice to not run the CO2 tank until it is empty is good advice.


----------



## Jeff5614 (Dec 29, 2005)

Agree with everyone else. You're pressure shouldn't start to drop until the liquid CO2 in the tank is gone and all you have left in the tank is CO2 in gaseous form which means you're almost empty. As Darkblade said, you should get at least 3 months at that bubble count if not more so I would think you have a leak somewhere.


----------



## PRSRocker3390 (Apr 20, 2009)

how should i go about checking for leaks exactly? And leaks in what, the tank or regulator? I mean I did purge off a bit of co2 from my mistake in the beginning. I really hope there isn't any leaks. It has been at 500psi now for a couple of days. What is the end of tank dump and how can i prevent it?


----------



## Darkblade48 (Jan 4, 2008)

You can check for leaks with some soapy water. Put it into a spray bottle and spray anywhere there is a connection (i.e. between the tank and the regulator). I doubt the initial purge from the beginning would have lowered your CO2 by much, unless you kept it open for an extended period of time.

End of tank dump is exactly what occurs when your CO2 tank is nearing empty. If you have a cheap regulator and a cheap needle valve, it is possible for all the remaining gas to dump into your tank.


----------



## PRSRocker3390 (Apr 20, 2009)

at what point does it dump? Just hand soap and water will work, correct?


----------



## PRSRocker3390 (Apr 20, 2009)

ok still pretty much at 500 psi. Maybe could it just be the normal pressure for my room. My house's central air is on 72 degrees. It might have went down but not by much. Like the tiniest smidge. But anyway, at what point should i refill? Like how long can it go before an end of tank dump? About 100 psi?


----------



## Darkblade48 (Jan 4, 2008)

PRSRocker3390 said:


> at what point does it dump? Just hand soap and water will work, correct?





PRSRocker3390 said:


> But anyway, at what point should i refill? Like how long can it go before an end of tank dump? About 100 psi?


It is hard to say whether a tank will dump or not. It is dependent on the quality of your regulator as well as your needle valve. With a good quality needle valve and regulator, you need not worry about end of tank dump at all, and can run your tank right up until it is empty.

If either your regulator or your needle valve is poor, however, watch out!

An end of tank dump may occur around 100 PSI.

As for checking leaks, you can use any kind of soap.


----------



## PRSRocker3390 (Apr 20, 2009)

Its a milwaukee regulator so I dont know what their reputation is with end of tank dumping.


----------



## Darkblade48 (Jan 4, 2008)

You will find that there are lots of varied opinions on needle valves and regulators. Some people have had no issues whatsoever with Milwaukee regulators (and their stock needle valves), while others have had nothing but trouble...

If you really are worried about end of tank dump, you could switch out your gas tank when it is at ~100 PSI.


----------



## Left C (Nov 15, 2003)

Hoppy posted some info about his Milwaukee regulator when the CO2 cylinder neared being empty.


----------



## Darkblade48 (Jan 4, 2008)

Here is the thread (that I believe) Left C is talking about:

http://www.plantedtank.net/forums/g...scussion/90433-co2-dump-more-info-needed.html


----------



## Left C (Nov 15, 2003)

Thanks! That's it.

Hoppy has a lot of information in his several posts in that thread. It is an excellent thread.


----------



## airborne_r6 (May 2, 2008)

I like dish soap better, I think it makes bubbles much better than hand soap.

edit:
I almost forgot, I have a 5lb tank running close to 3bps with a regulator similar to the milwaukee. I bought the setup used and the seller said the tank was no more than half full and it lasted 4 months before I refilled it. I would definitely say you have a leak.


----------

