# [Wet Thumb Forum]-Do I need to use a check valve?



## Jeremy S (Apr 9, 2006)

Do I need to use a check valve with my co2 system if Iâm using a needle valve?


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## Jeremy S (Apr 9, 2006)

Do I need to use a check valve with my co2 system if Iâm using a needle valve?


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## BobAlston (Jan 23, 2004)

I do.

Bob


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## imported_Platy (Feb 4, 2003)

Oh Yea,

God forbid something happens to the regulator, or a dump... the water will back syphin through the needle valve.

I have the one that Robert Sells here at aquabotanic, it works well and is well built. If you do get one, dont get one from like a meijer or walmert, those are junk and will leak co2 *guessing on past experience with regular o2*

Its like 18.00 but its worth it if you worry about it.

At least thats my 2 cents









Dustin

ImaNewbie -
125 Gal - 3.07wpg - 99% flourite - Pressurized Co2 - Uv Sterilization when needed - Densly Planted


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## Jeremy S (Apr 9, 2006)

Do you know where I can get a brass check valve?


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## ekim (Jan 31, 2004)

http://www.aquabotanic.com/shop/en-us/dept_16.html


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## Jeremy S (Apr 9, 2006)

Ekim, is the dupla check valve brass?


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## Jeremy S (Apr 9, 2006)

Do you think I could use this check valve from the clippard website? It looks allot like this brass one from marine depot.


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## DaveStall (Feb 14, 2003)

There is another solution if you don't feel like using a check valve or spending a ridiculous amount of money on a "CO2 proper" check valve. If you make sure your CO2 line runs higher that the water level, you won't have to worry about water siphoning back down and creating a mess. You can use whatever method that works best .. put a nail in the wall and loop the line over that, etc.

Personally, I use check valves because I have cats that like to do evil things and knocking the CO2 line off of its perch is right up their alley. I have been using the $3.00 brass check valves from my local pet store (Penn Plax brand I believe) with no problems.

Dave


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## david lim (Mar 30, 2004)

hey dave,
I just wanted to warn you that what determines backflow through the tubing is the change in pressure between the ends of the tube and not where the height of the tube resides. When the co2 tank runs out of air (and pressure) there will be a lot more pressure at the tube open to your aquarium compared to the amount of pressure at where your tube attaches to the regulator or in this case where your tube is open to the air (since the cylinder is empty). To make this work you have to have your entire co2 apparatus (cylinder and all) or at least the opening of the tubing above the aquarium water line. This way any water that runs back through the tube from your aquarium will equilibrate with atmospheric air at the tubing end open to the regulator since the pressure from atmospheric air will be even on both sides of the tubing. This is easily shown through experiments







.


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## DaveStall (Feb 14, 2003)

That's a good point .. I guess I should have stated that I have only used DIY (yeast) CO2 to this point, so I always have enough pressure in the system to prevent any problems. I worry about the little details anyhow, so the price for a check valve certainly gives me enough peace of mind to justify the cost.

Dave


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## gsmollin (Feb 3, 2003)

Actually, its all worse than that, because the tubing is full of CO2, not air. The CO2 will dissolve in the water, and the water will flow into the tubing. I have seen water flow vertically up through a CO2 filled line at the rate of 1 inch per hour. It will flow all the way back into your regulator if you don't have a check valve. In my system, the check valve is located at the inlet to the bubble counter, which is all attached to the back of the filter dip tube, above the water line. When the CO2 tank runs empty, I remove it to go for a refill. In that time (8 hours), the water routinely backs up into the bubble counter and refills it for me. The check valve stops it at that point.


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