# CO2 check valves



## Mr Fishies (Sep 21, 2007)

Is there anyplace locally to pick up good CO2 resistant check valves?

All I'm finding are ones that are for air pumps and I know if the valve internals are not the right material it will harden up and be useless.

Currently, I'm using a DIY bubble counter, so I suppose I could pick up a nicer counter with a built in check valve, but I like the idea of a separate check valve.


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## ameekplec. (May 1, 2008)

I was going to order some from a scientific supply house in Quebec:
http://www.coleparmer.ca/catalog/product_view.asp?sku=9855311

They're more expensive than your typical check valve, but it has a chemically resistant vitron seal and polypropylene body which makes it suitable for CO2 systems, unlike the regular ones typically seen in LFS.

Let me know if you'd be interested in getting them with me.


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## Mlevi (Jan 28, 2012)

I know this is an ancient thread, but the question's still as valid. Anyone have any recent thoughts on which check valve to use for a DIY CO2 system? Do you use one? If so, which one? Purchased from where? Would also love info about which ones to stay away from etc.


Al.


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## default (May 28, 2011)

Mlevi said:


> I know this is an ancient thread, but the question's still as valid. Anyone have any recent thoughts on which check valve to use for a DIY CO2 system? Do you use one? If so, which one? Purchased from where? Would also love info about which ones to stay away from etc.
> 
> Al.


For a DIY just use any one you can easily get, even the ones from ebay which are like 10-20 for $5 work as well. I use to just use the ones from AI and bigals and if it broke I just got another one.


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## Mlevi (Jan 28, 2012)

default said:


> For a DIY just use any one you can easily get, even the ones from ebay which are like 10-20 for $5 work as well. I use to just use the ones from AI and bigals and if it broke I just got another one.


I'm just worried about finding out the hard way that it didn't hold up...lol.
My tanks are near furniture that's MDF. I figure I need to try and make sure I don't come home to 'bloated' MDF someday. 

Al.


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## GAT (Oct 8, 2011)

Are you talking about yeast based DIY CO2? If so, you don't need a check valve. Fill the bottle with 85% water and you should be fine.


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## Mlevi (Jan 28, 2012)

GAT said:


> Are you talking about yeast based DIY CO2? If so, you don't need a check valve. Fill the bottle with 85% water and you should be fine.


Yes, its a Yeast based CO2 setup, but I want to place the bottle under the tank, on the stand. I am worried about siphon back flow, in the event that the pressure is the bottle is not adequate (towards the end of the yeast life, for example). The bottle is going to be atleast 4 Ft. under the water line. Unfortunately, with this one tank, I don't have anywhere to put the setup above the water line.

Al.


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## GAT (Oct 8, 2011)

there won't be any back flow. The bottle is already air tight even at the end of the yeast life. If the water were to siphon down where will it go? The reason we see the bubbles is because yeast is breaking down sugar into CO2 gas and alcohol. As the CO2 is being produced it looks for an easy way to get out and we provide that by airline tubing. When it stop bubbling means there is no yeast reaction but that doesn't mean there is no air. You still have CO2 in your bottle but its at an equilibrium pressure. In order for disaster to strike you basically have to unscrew the bottle and leave the cap hanging on the floor.

does that help?

As for check vale. Adding check valve can screw with your plan. DIY CO2 works best when you have less joints because it means less connections for your CO2 to escape. In my DIY CO2 reaction i just drilled a hole in the cap and pulled the airline through and the other end goes under the filter intake.


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## Mlevi (Jan 28, 2012)

GAT said:


> there won't be any back flow. The bottle is already air tight even at the end of the yeast life. If the water were to siphon down where will it go? The reason we see the bubbles is because yeast is breaking down sugar into CO2 gas and alcohol. As the CO2 is being produced it looks for an easy way to get out and we provide that by airline tubing. When it stop bubbling means there is no yeast reaction but that doesn't mean there is no air. You still have CO2 in your bottle but its at an equilibrium pressure. In order for disaster to strike you basically have to unscrew the bottle and leave the cap hanging on the floor.
> 
> does that help?


That definitely does help. Thanks!
Puts my mind at ease about going ahead with the placement.

Al.


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