# pressurized Co2 and check valves. do they create resitance and how many do you use?



## Aquaticfan (Oct 30, 2011)

Here is my questions. I know what I feel about this but someone stated to me that a check valve causes restrictions in the system of a pressurized co2 set up and running more then one check valve in line is not needed nor beneficial but yet creates to much restriction on the system. I doubt anyone has ever measured output into the tank after check valves or any of that. So what's the consensus and do you only run one check valve in your system? Do you feel having more then one adds a little more protection? Curious what people's thoughts are or if anyone has fact/data to show. Thanks


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## AheartlessFish (Mar 18, 2008)

I dont know much about the topic...but i can share with you what i found out for myself.

I used a plastic check valve on my co2 line. placed the co2 line in the water and i got the same bps as to when i took the check valve off. There was no co2 bps difference. I wouldnt know why you would want to use two...these things dont often fail? lol.

One thing i did notice tho is that the bps that was coming out of the unit (in the bubble counter) was ALOT faster than the bps coming out of the co2 line end. Im not sure why since the co2 line is tightly fitted onto the output of the bubble counter (Milwaukee brand regulator)

I read that the plastic can breakdown after a while with co2 contact...ive been using a plastic one for over 2 years now and i havent had problems with it...when submerged underwater along with the airline, i didnt notice any leaks. However im gona invest a 3-4 bucks into getting a brass one to be sure. Wouldnt hurt.

HTH


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## bosmahe1 (May 14, 2005)

I use two, one on either side of an inline bubble counter. I initially installed one between the bubble counter and diffuser. But when the co2 solenoid closed, I noticed water from the bubble counter entering the co2 line towards the needle valve and regulator. I guess back pressure can force water out of the bubble counter. Anyway, I added a second check valve between bubble counter and needle valve.


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## Left C (Jun 14, 2005)

Check valves have a cracking pressure rating. This is just like it sounds. This is the initial pressure that it takes to crack open the check valve. Below this pressure, the check valve closes. Some popular ones that we use require 1/3 psig, 1/2 psig and 1 psig. There are many other cracking pressure ratings for check valves.

The common Clippard brass check valve, MCV-1BB, that we use cracks at approximately 1/2 psig.

Anyway, I run a check valve before and after the bubble counter.

EDIT: Adding more to the OP's question.



Aquaticfan said:


> Here is my questions. I know what I feel about this but someone stated to me that a check valve causes restrictions in the system of a pressurized co2 set up and running more then one check valve in line is not needed nor beneficial but yet creates to much restriction on the system.


Listed above, you can see the common cracking pressures on check valves that we use. As an example, if we use 2 or 3 of the Clippard brass check valves, this results in a total of 1 to 1.5 psig cracking pressure. Also, it takes a bit more pressure for the valves to open more for whatever our working pressure is. Our regulators can easily overcome this.

There are atomizers that require 30+ psi around now. Many of our regulators can run these.

There may be some people that are using check valves with high cracking pressures. It is possible that they might have trouble.



Aquaticfan said:


> I doubt anyone has ever measured output into the tank after check valves or any of that.


Check valves have specs. But, as you say, I haven't read of any measurement tests. There might be a reason for this. It might not be needed unless there is a problem.



Aquaticfan said:


> So what's the consensus and do you only run one check valve in your system? Do you feel having more then one adds a little more protection? Curious what people's thoughts are or if anyone has fact/data to show. Thanks


I'm like bosmahe1. I run one before and one after my bubble counters. I've seen the fluid creep up too.

On Rex Grigg's site, he says the following about his DIY bubble counter: "Works best with two check valves. One on each side of bubble counter." I like his suggestion.
LINK: http://www.bestaquariumregulator.com/CO2.html#bc


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## Newt (Apr 1, 2004)

I only use one placed just above the top of the tank. Never had an issue.


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