# Is a Co2 check valve needed?



## Cardoc

Yes it is very needed unless you like spending money, even a cheap one is better than nothing, but spend the money on a good one I ruined my tank stand because I had a cheap check valve and it let water back into my diy set up. I run two good check valves now one before the bubble counter and one before my reactor. 
You can check for leaks by spraying all fittings with soapy water and looking for bubbles.


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## Aquaticfan

Hey Chad!!

Well, Its not a matter of your Co2 tank filling up with water.. Its all about protecting your regulator, Solenoid, Needle valve and the like from water damage. If the water gets to it it can and will ruin that stuff. Can cost you a pretty penny. Are Check valves worth it? yes. Cheap insurance for not killing the above items. Can it be a potential for a spot that leaks? Yes. But so can your CGA320 fitting, Any spot you have threads. Your gauges, Any where you have connected hose/tubing. Any needle valve... All of these are hi potential of leaks. Not any different then the check valve. In all of my Co2 systems I run Check valves. I run one right at the tank if its a diffuser or just before the diffuser. If its a reactor I run it just before the reactor. Then I also have some set ups with in line bubble counters. Like the glass ada ones. I use a check valve before those so the liquid in them stays in them. Then I run a check valve right as the last thing of the regulator assembly. So... Max in all I could have 3 check valves in a single system. Or 2. Anything made by human hands can go bad. So it can happen. If it were me a couple buck check valve Vs any of the parts of my regulator is well worth it. Normally btw the issue is when your Co2 shuts off at night you can get back flow.


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## maknwar

Put your co2 regulator above your water and you won't need one.


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## Aquaticfan

But the question is, how many if us can do that? On all my set ups its not possible. Besides. I'm not to keen on the idea if a 15lb co2 tank that weighs more then that above or near my head level.


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## maknwar

Me either, that's why I just put a check valve on the hose and not worry.


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## Aquaticfan

maknwar said:


> Me either, that's why I just put a check valve on the hose and not worry.



LOL.... :icon_lol:


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## talontsiawd

Just replace it. Use a airline one for temp if you can't get a brass or SS one locally and have to order it. Not only is water bad for the regulator, remember you have a solenoid you don't want water to get into either.


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## t2ak

Maybe a dumb question but how does the water from a bubble counter not enter the regulator after the pressure is gone? I have a milwalkee regulator that has the bubble counter built in.


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## prighello

t2ak said:


> Maybe a dumb question but how does the water from a bubble counter not enter the regulator after the pressure is gone? I have a milwalkee regulator that has the bubble counter built in.


I think that counter might have a built in check valve.


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## t2ak

prighello said:


> I think that counter might have a built in check valve.


I will look into that. I have one on the line. I was just curious about the bubble counter.


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## talontsiawd

t2ak said:


> Maybe a dumb question but how does the water from a bubble counter not enter the regulator after the pressure is gone? I have a milwalkee regulator that has the bubble counter built in.


The bubble counters that go on the regulator have an integrated check valve. However, some people go the extra step and put another check valve under it. You can get a threaded check valve that is like a fitting. You install between the needle valve and bubble counter. It's a good idea, be it with a on reg bubble counter or not. In insures you have a check valve at the absolute closes point to your regulator/post body setup.


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## t2ak

after looking at it, I dont see how they could possibly fit a check valve on it. it sit directly on top of the needle valve.


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## talontsiawd

t2ak said:


> after looking at it, I dont see how they could possibly fit a check valve on it. it sit directly on top of the needle valve.


It looks nothing like an inline check valve. 

Here is an example
http://www.mscdirect.com/product/04..._sJXegN7a0_PLA__15557577904_c_S&026=-99&025=c


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## DarkCobra

maknwar said:


> Put your co2 regulator above your water and you won't need one.


This won't help.

When CO2 is shut off, either for the night or due to failure/blackout/whatever, water keeps absorbing whatever CO2 is left. This creates a vacuum which draws water progressively further up the line. And given enough time, perhaps a few days, into things you never want water in. Makes absolutely no difference if the CO2 system is above tank level.

Only a check valve prevents this without manual intervention.


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## t2ak

looks like I am safe then with the regulator one and the one i have on the tubing. thanks for your help.


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## PlantedRich

DarkCobra said:


> This won't help.
> 
> When CO2 is shut off, either for the night or due to failure/blackout/whatever, water keeps absorbing whatever CO2 is left. This creates a vacuum which draws water progressively further up the line. And given enough time, perhaps a few days, into things you never want water in. Makes absolutely no difference if the CO2 system is above tank level.
> 
> Only a check valve prevents this without manual intervention.


I feel this is wrong. Faulty science perhaps? Water does absorb some CO2, however isn't there is a definite limit to how much the small portion of the water exposed to the CO2 will absorb. Even if we used a rather large diameter tube and said we had a 1/4 " cross section, how much CO2 will a 1/4" cross section of water absorb? Enough to absorb even a short length of tubing like 6 inches? If water absorbs CO2 so easily, why do we worry about it gassing off? Would we not be having quite the reverse problem with the water sucking too much CO2 back into the tank water? 
I don't see this happening in my setup which I run without check valves. When CO2 is trapped between my solenoid and my bubble counter which I locate below my other equipment, the water does not run uphill. 
Maybe water is more dense than gas and it has to wind up on the bottom?


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## DarkCobra

PlantedRich said:


> Even if we used a rather large diameter tube and said we had a 1/4 " cross section, how much CO2 will a 1/4" cross section of water absorb?


It's not a matter of how _much_ when that cross-sectional interface is connected to the tank, because the tank can absorb plenty. It's just a matter of how _fast_. Try filling a section of 1/8" line with CO2. Close off both ends with hemostats. Suspend it over the tank, with the bottom end in the water, and release the bottom hemo. Wait an hour or two. You'll see the water travel straight up.

And you'll see that it's not fast enough to cause serious problems when turning off CO2 overnight. Typically we notice nothing more than just a slow start on some diffusers, as it has to force out the more viscous water that's been drawn in.

But interrupt CO2 for a few days and it can make it much farther.



PlantedRich said:


> I don't see this happening in my setup which I run without check valves. When CO2 is trapped between my solenoid and my bubble counter which I locate below my other equipment, the water does not run uphill.


That's right. The water volume in the bubble counter is limited, and not connected to the main tank volume. So it can become saturated with CO2, and in fact it's _always_ saturated by virtue of having 100% pure CO2 bubbled though it. Shut off the solenoid, doesn't matter, it simply can't absorb any more. Water only backtracks beginning with where the CO2 enters the tank.


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## jeremy va

Definitely happens. Never knew why until now. Thanks!

Now all we need are check valves that actually work. Most fail IME -- cheap or expensive. They slow the water down so I've never had a disaster but you sure as heck can't count on them...


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## Sean W.

its interesting that this thread is here. i was setting up my co2 reactor today, i had the co2 line going into the reactor, i just plugged it with a short run of tubing and put a check valve on the end while i set up the rest of the system, came back a few minutes later and water was slowly leaking out of the check valve.. what gives?


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## jeremy va

What gives is that you got hornswoggled like the rest of us. Check valves ALWAYS fail. -(


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## Sean W.

so a bubble counter is better than a check valve?


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## RLee

Sean W. said:


> so a bubble counter is better than a check valve?


The one thing I have noticed is that check valves in bubble counters that are filled with glycerin or mineral oil last longer. My guess is that the previous prevent corrosion of the check valve.


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## jeffkrol

Lesson for the day.. YES water will back up if there is no check valve..
And it doesn't hav to take long either.. 

Just found that out the hard way..
Mine backed up overnight all the way to the solenoid .. Hopefully no farther..It's a new install and I'm just getting my feet (well more than feet) wet in it.

As a side question:
Best way to flush/dry the regulator to be sure.. short of dis-assembly..


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## Steve002

Can anyone comment on the possibility of water backing through an in-line diffuser? With 30 psi pressure needed to force CO2 gas through it I can't see how water with no pressure can back through.


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## goneRogue

Steve002 said:


> Can anyone comment on the possibility of water backing through an in-line diffuser? With 30 psi pressure needed to force CO2 gas through it I can't see how water with no pressure can back through.


Water is dense. On a small tank you have at least 12" of head pushing on the diffuser. Once the gas in the diffuser and the line is gone all that water pressure has to go somewhere and the path of least resistance is the diffuser.


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## devilduck

Water in an inline diffuser is normal. The diffuser fills with water when it is off. Once the co2 is back on the water will be driven out. You just need to add 30 minutes or so to account for this.


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## DarkCobra

Steve002 said:


> Can anyone comment on the possibility of water backing through an in-line diffuser? With 30 psi pressure needed to force CO2 gas through it I can't see how water with no pressure can back through.


It does, have seen it with a GLA Inline Atomic. This is the reason why a "virgin" diffuser will immediately start right up with 30psi, but after a CO2 shutdown, it takes longer to start up subsequently - it has to push water out the fine pores which is much harder. 30 minutes may be typical but that can vary. At 30psi I waited an hour and still no CO2, cranked it to 35psi and had reasonable startup times after that.


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## Steve002

Thanks, I'd better get that check valve installed then.


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