# What is the cheapest two stage CO2 regulator?



## deepgreen1 (Mar 15, 2015)

Hello everybody,
After using a standard regulator for a decade and watching bubble counts change with every change in pressure in the CO2 tank including gasing shrimp and fish in the gas dump of nearly empty gas tanks, I finally want to switch to a two stage regulator. The cheapest I found is a Harris 9296 with neopren diaphragma for $217 without needle valve and solenoid. Is there any other two stage regulator that is cheaper? I suppose that every two-stage regulator is superior to a one-stage regulator in stable CO2 release.
Thanks.


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## clownplanted (Mar 3, 2017)

http://nilocg.com/dual-stage-regulator-na-ss-pro-dual-stage-stainless-steel-regulator/


Sent from my iPhone using Tapatalk


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## burr740 (Feb 19, 2014)

https://www.co2art.co.uk/collections/dual-stage-regulators

I have one of these. pretty good reg, no EOTD. I dont particularly like the needle valves they come with, but for the money its about as good as you can expect.


GLAs are single stage but they claim to have no EOTD. 

Aquarium CO2 Regulator | Green Leaf Aquariums

I have a Gro 1, and while its nothing compared to what you'd get with a cheapo single stage, there's still a slight increase if you let the tank run bone dry. At least mine does. Otherwise it's a damn good regulator.


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## lksdrinker (Feb 12, 2014)

deepgreen1 said:


> Hello everybody,
> After using a standard regulator for a decade and watching bubble counts change with every change in pressure in the CO2 tank including gasing shrimp and fish in the gas dump of nearly empty gas tanks, I finally want to switch to a two stage regulator. The cheapest I found is a Harris 9296 with neopren diaphragma for $217 without needle valve and solenoid. Is there any other two stage regulator that is cheaper? I suppose that every two-stage regulator is superior to a one-stage regulator in stable CO2 release.
> Thanks.


Sounds like you need a better needle valve and not necessarily a "better" regulator to correct the bubble count that changes. As far as gassing your fish....make sure you dont let the tank get that close to empty and you shouldn't have a problem.


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## Bunsen Honeydew (Feb 21, 2017)

lksdrinker said:


> Sounds like you need a better needle valve and not necessarily a "better" regulator to correct the bubble count that changes. As far as gassing your fish....make sure you dont let the tank get that close to empty and you shouldn't have a problem.


A dual stage regulator would obviate the need to adjust though. Isn't that the point of the 2 stage is to deliver consistent pressure to the needle valve?


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## Mike16T (Jun 13, 2016)

I think a the nilocG regulator is cheaper in the long run knowing that it has 10 years warranty vs GLA's 6 years warranty


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## deepgreen1 (Mar 15, 2015)

clownplanted

This looks like a solid device and the 10 year warranty is excellent and the price is again excellent. I however wonder why a range up to 350PSI for the working pressure has been selected. I usually set my pressure to 15PSI with my diffuser. Do you have it yourself and for how long? 

burr740
I would have not thought that it is possible to get a complete two stage device for that price. This looks like the most economic version I ever saw. Did you import it into the US and if so how easy did it go with customs?
The GRO1 looks like a good solution, too. My regulator worked fine for the first years with little EOTD, but I have the impression it got worse over time with the last years leading to said gassing of fish and shrimp. I have to say I have it now for 10 years. Nevertheless, I am wondering how the single stage regulators compare to two stage in the long run. How long do you have yours?

Iksdrinker
I was wondering about the needle valve as well. In my system, bubble counts however only change with pressure changes in the tank, such as equilibration of temperatur after a refill, changes in the room temperature and apparently EOTD. I was under the impression that a failing needle valve leads to varying bubble counts at constant tank pressure.

Thanks everybody for your advice.


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## burr740 (Feb 19, 2014)

deepgreen1 said:


> burr740
> I would have not thought that it is possible to get a complete two stage device for that price. This looks like the most economic version I ever saw. Did you import it into the US and if so how easy did it go with customs?
> 
> The GRO1 looks like a good solution, too. My regulator worked fine for the first years with little EOTD, but I have the impression it got worse over time with the last years leading to said gassing of fish and shrimp. I have to say I have it now for 10 years. Nevertheless, I am wondering how the single stage regulators compare to two stage in the long run. How long do you have yours?


CO2Art ships to the US no problem. They have three shipping options, going off memory for the rates but you get the idea - Regular shipping around $7 and will take at least a month. The next option is about twice that and takes 2-3 weeks, The premium shipping is like $35 and gets here in about a week.

Ive ordered from them probably 4 times, using various shipping plans and it works about like they say.

Ive had the GLA reg about two years.


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## leaf (Jun 27, 2009)

Dual stage regs are commonly used in welding and beer/beverage dispensing. These are just as good as any, though of course dont go too cheap or you'll run into some baddies. The one I have right now is for beverage and cost less than $70, but I had to source the needle valve, bubble counter, and solenoid separately. I can't imagine a reg performing any better - holds low pressure on the dot 24/7, and no suck back when solenoid is off.


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## Jeff5614 (Dec 29, 2005)

I've made one purchase from CO2 Art and it was pain free. I opted for the free shipping option and the item arrived in about a week in good shape. If I were looking for a new regulator I would be tempted to give theirs a try with the upgraded needle valve for an additional $10. 

I jumped on the two stage bandwagon when they first started becoming popular and everyone was buying used from *bay and adding their own needle valve, solenoid, etc. It was a pretty good deal. A used dual stage Victor for $35 plus the aforementioned parts and it's still rock solid eight years later. Before the dual stage I was using a single stage Cornelius that I had bought complete with Clippard needle valve and solenoid. It was hard keeping a bubble count that I didn't have to adjust daily. I finally sprang for an Ideal needle valve and that made all of the difference. The bubble count held steady from day to day but it would begin to pick up some as the cylinder emptied, but nothing like you hear about in the EOTD stories and was easily adjusted until I could get a refill.

Long story short, you might consider just replacing the needle valve and see how that does. It could save you some money, or not.


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## deepgreen1 (Mar 15, 2015)

It seems CO2 Art is the way to go unless I find such a cheap regulator like the one leaf pointed out.

Leaf, is the regulator that you pointed out still available?

Jeff5614, the bubble count remains constant when the tank drains without any disturbance until the liquid CO2 is used up. In the beginning, I actually had the needle valve completely open and just used the regulator for adjusting flow. I am not sure whether this is a correct way to do this without damaging the regulator. Maybe I damaged it by doing this, LOL? In any case, it worked fine for the first years. Only after it started to show increased EOTDs, I began using the needle valve. But at that point, it did not help. I may get first the needle valve and then get the regulator just to see whether it could have been the needle valve.

Thanks again everybody.


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## lksdrinker (Feb 12, 2014)

Bunsen Honeydew said:


> A dual stage regulator would obviate the need to adjust though. Isn't that the point of the 2 stage is to deliver consistent pressure to the needle valve?


No. The regulator does exactly as the name implies....it regulates the pressure. Any working regulator should delivery consistent pressure to the needle valve (assuming you have gas in the tank anyway). A dual stage regulator and a single stage regulator should both do the job of regulating equally well. Single stage regulators can be problematic when your gas is almost empty as the OP has been experiencing. When the pressure in the tank drops some single stage regulators are unable to do their job and instead of regulating pressure they can expel whatever is left in the tank. In theory a dual stage regulator wont do that. However, if a co2 tank is close enough to empty where its a problem for a single stage reg, then you need a new tank of gas no matter what regulator you have!



deepgreen1 said:


> Iksdrinker
> I was wondering about the needle valve as well. In my system, bubble counts however only change with pressure changes in the tank, such as equilibration of temperatur after a refill, changes in the room temperature and apparently EOTD. I was under the impression that a failing needle valve leads to varying bubble counts at constant tank pressure.
> 
> .


Maybe I've been lucky, but I run a single stage reg with fabco needle valves and I get a constant rate of gas no matter whats going on in the tank. I just make sure not to let the tank run down close to empty.


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## lksdrinker (Feb 12, 2014)

deepgreen1 said:


> the bubble count remains constant when the tank drains without any disturbance until the liquid CO2 is used up. In the beginning, I actually had the needle valve completely open and just used the regulator for adjusting flow. I am not sure whether this is a correct way to do this without damaging the regulator. Maybe I damaged it by doing this, LOL? In any case, it worked fine for the first years. Only after it started to show increased EOTDs, I began using the needle valve. But at that point, it did not help. I may get first the needle valve and then get the regulator just to see whether it could have been the needle valve.


I dont know if you could have damaged the reg using it this way. But, thats not how the system is designed to be used. (If you could leave the needle valve wide open and then adjust via the regulator why would you even need the needle valve to begin with?) You want to set the regulator to whatever pressure you might need (anywhere from 5 to maybe 35 PSI depending on your method of dispersion). Then you fine tune it via the needle valve. All the needle valve is doing is taking that 5-35 PSI and decreasing/slowing the dispersion of gas down even more into bubbles per second (and the needle valve will never do anything to prevent end of tank dump). You should aim to never touch anything on the regulator itself other than when you first set it up and again when its time for a new tank of gas. I think you're missing the idea on part of this and you kind of hit it on the head when you say there is no disturbance until the "liquid co2 is used up". (You might have the thought process backwards as you're using the gas not the liquid) But either way, the system is working fine up until you run out of gas! That implies to me that the system could be perfectly fine and you just need to get a new tank of gas a little sooner than you'd like to! Your description above is sort of like saying "I need a new car because it stops working every time it runs out of gas". Granted though a dual stage regulator should prevent end of tank dump so if you were not paying attention and your co2 ran dry then there would be no disaster in your aquarium at least.....but you would still need a new tank of gas!


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## Bunsen Honeydew (Feb 21, 2017)

lksdrinker said:


> No. The regulator does exactly as the name implies....it regulates the pressure. Any working regulator should delivery consistent pressure to the needle valve (assuming you have gas in the tank anyway). A dual stage regulator and a single stage regulator should both do the job of regulating equally well. Single stage regulators can be problematic when your gas is almost empty as the OP has been experiencing. When the pressure in the tank drops some single stage regulators are unable to do their job and instead of regulating pressure they can expel whatever is left in the tank. In theory a dual stage regulator wont do that. However, if a co2 tank is close enough to empty where its a problem for a single stage reg, then you need a new tank of gas no matter what regulator you have!
> 
> 
> 
> Maybe I've been lucky, but I run a single stage reg with fabco needle valves and I get a constant rate of gas no matter whats going on in the tank. I just make sure not to let the tank run down close to empty.


I think that the disparity between single and multistage is being undersold a bit here, but I can understand that if your experience is primarily in CO2, since it tempers the problem quite a bit.


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## lksdrinker (Feb 12, 2014)

Bunsen Honeydew said:


> I think that the disparity between single and multistage is being undersold a bit here, but I can understand that if your experience is primarily in CO2, since it tempers the problem quite a bit.


In all honesty my experience is not primarily with CO2 but only with CO2 lol. (well and cheapo regulators on things like air compressors). But I thought the theory was pretty much the same for any gas? Single stage reg takes high pressure from the tank and uses a single diaphragm to decrease the pressure and then a needle valve can be used to fine tune the flow rate. Dual state uses a pair of diaphragms (I assume one decreases to a certain pressure and the 2nd decreases even further?....or are they both decreasing to the same and one is simply a failsafe?) to decrease the high pressure from the tank and then a needle valve is still needed if you wish to fine tune the flow rate more.


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## Bunsen Honeydew (Feb 21, 2017)

lksdrinker said:


> In all honesty my experience is not primarily with CO2 but only with CO2 lol. (well and cheapo regulators on things like air compressors). But I thought the theory was pretty much the same for any gas? Single stage reg takes high pressure from the tank and uses a single diaphragm to decrease the pressure and then a needle valve can be used to fine tune the flow rate. Dual state uses a pair of diaphragms (I assume one decreases to a certain pressure and the 2nd decreases even further?....or are they both decreasing to the same and one is simply a failsafe?) to decrease the high pressure from the tank and then a needle valve is still needed if you wish to fine tune the flow rate more.


Regulator performance varies a bit by input pressure, which is why multiple regulators are better at giving consistent output because it tightens the variance in pressure on the last regulator. Since CO2 condenses at tank pressure, the pressure above the liquid is pretty consistent in a (mostly) closed system, which kind of serves as a regulator of sorts. Having done a fair amount of chemistry with gases that don't condense, there is a larger variance in output over the range of the tank. I have been told to never use single stage regulators for gases when differing outputs could have serious consequences, such as chlorine.


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## lksdrinker (Feb 12, 2014)

Bunsen Honeydew said:


> Regulator performance varies a bit by input pressure, which is why multiple regulators are better at giving consistent output because it tightens the variance in pressure on the last regulator. Since CO2 condenses at tank pressure, the pressure above the liquid is pretty consistent in a (mostly) closed system, which kind of serves as a regulator of sorts. Having done a fair amount of chemistry with gases that don't condense, there is a larger variance in output over the range of the tank. I have been told to never use single stage regulators for gases when differing outputs could have serious consequences, such as chlorine.


Interesting. I knew there had to be a reason why dual stage regulators exist....I knew it couldn't be simply to prevent EOTD in an aquarium!


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## jeffkrol (Jun 5, 2013)

Can't recommend current CO2 art 2 stage.. Still seems hit or miss as to quality..
They had a better one (at over 2x the price of current one) which they no longer sell..


There are no cheap CO2 2 stage regulators really..At least in "my" opinion..
There is a group of Chinese 2 stage regs that seem to come and go, like the Nilogc, sold under a few diff.
names, inc. "used to be sold" at CO2 Art.
Like this:
Aqua Labs || CO2 Regulators - View All


Uniweld RHT8013 Medium/Heavy Duty Two Stage CO2 Regulator with CGA320 Inlet, New
JUST the reg.. $279..

Technically one could piece together a "commercial rated" Reg and part up to the bubble counter for $400.
a lot less w/ some luck..
https://www.bakersgas.com/SMI35-50-580.html?gclid=COWu94bjvdQCFQQpaQod26AFSA
$208 plus $10 and sweat equity gets you a CO2 reg..
NOTE: N2 max pressure is 50psi.. There is an O2 one at about the same price w/ max at 125psi
http://weldfabulous.com/miller-smit...306607222949&gclid=CNvTkJ3mvdQCFQKHaQodFKkB4A 

solenoid and needle would be a kit for $90..
CO2 Regulator Parts | CO2 For Planted Tanks And Home Brewing. CO2 Regulator Post Body Kit #1 (12v)

Would need a 12v wall wart and bubble counter..
$300.. 
Advantage:
comercial reg
Clippard cool running solenoid
Fabco needle valve

CONs: 
Need to disassemble/assemble and get a few more parts..

as MUCH as I'd love to see a really really trustworthy 2 stage @ sub-$200 level..not seeing it currently..
Ganging 2 one stages together to effectively make a 2 stage is a theoretical option...and even likely cheaper...


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## Bunsen Honeydew (Feb 21, 2017)

lksdrinker said:


> Interesting. I knew there had to be a reason why dual stage regulators exist....I knew it couldn't be simply to prevent EOTD in an aquarium!


Lol, yep that is when you are going to see the biggest swing in pressure, when the liquid is gone. You still have some compressed gas left, so it is more like wanting to drive your car after the low gas light comes on that wanting to drive it after the gas runs out. In either situation though it would be prudent to get a refill. :grin2:

Bump:


jeffkrol said:


> Can't recommend current CO2 art 2 stage.. Still seems hit or miss as to quality..
> They had a better one (at over 2x the price of current one) which they no longer sell..
> 
> 
> ...


That is an interesting idea. I can't think of a reason why that wouldn't work. Hopefully someone can shed some light there.


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## mgeorges (Feb 1, 2017)

I would go with GLA's cheapest ($205) single stage regulator honestly. I run two of these, I have never had a tank dump and I run my tanks dry. Great warranty, based here in the US which is HUGE as I found out the hard way. I first bought a regulator from co2supermarket based in the UK. You have to buy special adapters for them since UK doesn't use CGA 320 on their CO2 tanks. I found this just adds another spot for them to leak from. You have to buy special o-rings, I never did find these o-rings locally so I had to order from UK and wait...maybe I didn't look hard enough. To be honest, the regulator I got from the UK just seems cheap...very cheap in comparison to the GLA regulators. Very solid build.


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## jeffkrol (Jun 5, 2013)

There is really no mechanical difference between the 2..









1st "stage" would run 125psi or greater.. second at working pressure..


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## deepgreen1 (Mar 15, 2015)

lksdrinker said:


> I dont know if you could have damaged the reg using it this way. But, thats not how the system is designed to be used. (If you could leave the needle valve wide open and then adjust via the regulator why would you even need the needle valve to begin with?) You want to set the regulator to whatever pressure you might need (anywhere from 5 to maybe 35 PSI depending on your method of dispersion). Then you fine tune it via the needle valve. All the needle valve is doing is taking that 5-35 PSI and decreasing/slowing the dispersion of gas down even more into bubbles per second (and the needle valve will never do anything to prevent end of tank dump). You should aim to never touch anything on the regulator itself other than when you first set it up and again when its time for a new tank of gas. I think you're missing the idea on part of this and you kind of hit it on the head when you say there is no disturbance until the "liquid co2 is used up". (You might have the thought process backwards as you're using the gas not the liquid) But either way, the system is working fine up until you run out of gas! That implies to me that the system could be perfectly fine and you just need to get a new tank of gas a little sooner than you'd like to! Your description above is sort of like saying "I need a new car because it stops working every time it runs out of gas". Granted though a dual stage regulator should prevent end of tank dump so if you were not paying attention and your co2 ran dry then there would be no disaster in your aquarium at least.....but you would still need a new tank of gas!


The problem is that I am sometimes away for a few days and there is no way that I can accurately predict when the gas tank runs empty unless I weigh it because of the strange way pressurized CO2 behaves compared to other pressurized gases. The pressure in the tank remains constant as long as there is still some liquid CO2 in the tank, because CO2 liquefies around 1100PSI (my tank pressure) and there is an equilibrium between liquid and gaseous phase of CO2 in the tank. Only when the liquid phase is used up and only gas is remaining, the pressure in the tank drops. This is only a few days before it totally runs empty. However, this is the time when the one stage regulator seems to stop regulating accurately because of the associated pressure drop. If I miss the time point when the liquid CO2 phase is used up and the pressure drops in the tank, one day might be sufficient to kill my animal life due to the strong EOTD. Therefore, it pays for me to have a system that is unaffected by the pressure drop in the CO2 tank shortly before it runs completely empty.

The needle valve in standard industrial gas tanks is primarily used as a shut-off valve because you do not want to shut off the main tank every time you are done. In the aquarium hobby, the solenoids do this job to shut the gas flow off automatically over night to save gas. From this perspective, I was indeed wondering why you would need an additional needle valve to regulate the gas flow because your regulator does this job already and the solenoid shuts off the flow. Thus, I was initially wondering whether the additional needle valve has to do something with the single stage, but after reading some discussions this seems not to be the case.


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## jeffkrol (Jun 5, 2013)

> I was indeed wondering why you would need an additional needle valve to regulate the gas flow because your regulator does this job already and the solenoid shuts off the flow.


One that is basically wrong.. Valve on the tank is (supposed to be) purely on/off..and your regulating un-regulated (as to pressure) gas..

and secondly, at our low flow rates you need much greater precision


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## deepgreen1 (Mar 15, 2015)

jeffkrol said:


> Can't recommend current CO2 art 2 stage.. Still seems hit or miss as to quality..
> They had a better one (at over 2x the price of current one) which they no longer sell..
> 
> 
> ...



This is what I was thinking, get an industrial one and add the parts. The cheapest I found is the Harris 9296 with 50 or 125 PSI working pressure. They are currently on sale here for $217 (regular $367):

https://www.weldingmart.com/harris-model-9296-two-stage-regulator

I will look into your suggestions and compare. Thanks.


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## Bunsen Honeydew (Feb 21, 2017)

jeffkrol said:


> There is really no mechanical difference between the 2..
> 
> 
> 
> ...


I get it, its just usually when I see something that seems that simple it is because I am missing something.


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## deepgreen1 (Mar 15, 2015)

jeffkrol said:


> Can't recommend current CO2 art 2 stage.. Still seems hit or miss as to quality..
> They had a better one (at over 2x the price of current one) which they no longer sell..
> 
> 
> ...


This is what I initially planned, get an industrial one and add the other part. I found a Harris 9296 for $217 one sale here (regular price $367):

https://www.weldingmart.com/harris-model-9296-two-stage-regulator

Thanks for your several suggestions. I will check how they compare to the Harris.


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## jeffkrol (Jun 5, 2013)

> Two-Stage (Dual Stage) Regulator
> A two-stage pressure regulator is ideal for applications with large variations in the flow rate, significant fluctuations in the inlet pressure, or decreasing inlet pressure such as occurs with gas supplied from a small storage tank or gas cylinder.
> 
> With most single-stage regulator regulators, except those that use a pressure compensated design, a large drop in inlet pressure will cause a slight increase in outlet pressure. This happens because the forces acting on the valve change, due to the large drop in pressure, from when the outlet pressure was initially set. In a two-stage design the second stage will not be subjected to these large changes in inlet pressure, only the slight change from the outlet of the first stage. This arrangement results in a stable outlet pressure from the second stage despite the significant changes in pressure supplied to the first stage.


What is not often mentioned is how close to "critical" are you running your CO2..
It is possible and likely that that tank running 50% of a toxic level of CO2 can easily absorb a "hit" from a tank dump..
If you are running 90% lethal concentration even a small dump could be fatal.. 

There is little doubt that a 2 stage is better equipt to handle changing inlet pressure better than a 1 stage..

Bump:


Bunsen Honeydew said:


> I get it, its just usually when I see something that seems that simple it is because I am missing something.


Whats missing is the hassle and space needed..


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## Bunsen Honeydew (Feb 21, 2017)

jeffkrol said:


> Whats missing is the hassle and space needed..


For sure. I did a little looking around on Amazon and it looks like suitable single stage brewing regulators (there are quite a few needle valves being sold as regulators too) are only around $40. If I had a CO2 setup already, I might dick around with it a bit. If you could just plumb one into on of the Dici single stage setups, one could get a setup (minus the tank) for about $100. I need to find an excuse to build one for work now. 

Come to think of it, I think that I have a regulator sitting in a drawer in my lab. >


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## jeffkrol (Jun 5, 2013)

> What is the difference between a two-stage and one-stage pressure regulator? A two-stage regulator reduces the pressure in two steps. In the first stage the high pressure gas is reduced to a pre-set intermediate pressure level, then reduced again in the second stage to the manually adjusted value desired by the operator. This two step reduction provides steady gas delivery throughout the discharge of almost the full cylinder contents. This is why two-stage regulators are used whenever the discharge pressure of a system must be precisely maintained. Two-stage regulators are generally used whenever the compressed gas cylinder pressure exceeds 1000 psig. Cylinders having a pressure less than 1000 psig are generally fitted with a one-stage regulator since the advantage of the two-stage regulator is minimized by the lower inlet pressure.


And remember most here were buying commercial 2 stages on eek bay for less than $50.. 



> Solid forged brass body contains two regulators. First stage reduces full cylinder pressure.
> Second stage delivers a constant pressure to the regulator outlet.


https://us.vwr.com/assetsvc/asset/en_US/id/14744560/contents


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## deepgreen1 (Mar 15, 2015)

jeffkrol said:


> Can't recommend current CO2 art 2 stage.. Still seems hit or miss as to quality..
> They had a better one (at over 2x the price of current one) which they no longer sell..
> 
> 
> ...



Using industrial two-stage regulators was my original idea. I found the Harris 9296 for $217 on sale here (regularly $367).

https://www.weldingmart.com/harris-model-9296-two-stage-regulator

Thanks for the other suggestions. Now I have something to compare.

The assembly of two one-stage regulators is interesting indeed. Do they have a minimum inlet pressure requirement?


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## deepgreen1 (Mar 15, 2015)

jeffkrol said:


> One that is basically wrong.. Valve on the tank is (supposed to be) purely on/off..and your regulating un-regulated (as to pressure) gas..
> 
> and secondly, at our low flow rates you need much greater precision


Yes, indeed. Pressure is not the same as flow. The regulator controls pressure and the needle valve controls flow. Only if there is a subsequent device with own flow control which happens in many industrial contexts, the needle valve is not needed for that purpose. 
In my original situation when I did not use the needle valve, I obviously controlled flow through pressure adjustments which worked due to sufficient resistance of my diffuser.

Thanks for the suggestions about alternative sources for industrial two-stage regulators. I originally had a Harris 9296 in mind which is sold here for $217 (regular price $367). 

https://www.weldingmart.com/harris-model-9296-two-stage-regulator

Now I have something to compare.

Your idea about using two single stage regulators is interesting indeed. Do you know whether there is a minimum required inlet pressure?


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## jeffkrol (Jun 5, 2013)

single stage (and any) regulator works till the tank is empty.. .. In other words down to zero inlet pressure..
Take it as a general statement.. sure there could be exceptions..


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## lksdrinker (Feb 12, 2014)

deepgreen1 said:


> The problem is that I am sometimes away for a few days and there is no way that I can accurately predict when the gas tank runs empty unless I weigh it because of the strange way pressurized CO2 behaves compared to other pressurized gases.


Well you can surely get an idea of how long your tank (what size co2 tank do you have?) should last in your setup. If nothing else changes then however long it takes to empty one tank should be about the same for the next and you can get at least a ballpark idea of when you may be close to running out. 



deepgreen1 said:


> The needle valve in standard industrial gas tanks is primarily used as a shut-off valve because you do not want to shut off the main tank every time you are done. In the aquarium hobby, the solenoids do this job to shut the gas flow off automatically over night to save gas. From this perspective, I was indeed wondering why you would need an additional needle valve to regulate the gas flow because your regulator does this job already and the solenoid shuts off the flow. Thus, I was initially wondering whether the additional needle valve has to do something with the single stage, but after reading some discussions this seems not to be the case.


I dont know about "needle valves" used in other applications; but I dont think they are ever intended to be used as a shut off valve. You risk damage to the needle if you try to "close" it fully.


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## klinger988 (Jun 6, 2017)

burr740 said:


> deepgreen1 said:
> 
> 
> > burr740
> ...


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## Bunsen Honeydew (Feb 21, 2017)

lksdrinker said:


> Well you can surely get an idea of how long your tank (what size co2 tank do you have?) should last in your setup. If nothing else changes then however long it takes to empty one tank should be about the same for the next and you can get at least a ballpark idea of when you may be close to running out.
> 
> 
> 
> I dont know about "needle valves" used in other applications; but I dont think they are ever intended to be used as a shut off valve. *You risk damage to the needle if you try to "close" it fully.*


It only took me about 4 "ruined" needle valves to figure this out.


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## cwnannwn (May 23, 2017)

Wow, 200 bucks for a regulator. Dang. I always have gone with the cheaper co2 regulators from brew and soda stores. The are two stages, one reduces tank pressure down to 40-120psi and the next reduces it down to what you set it to. They cost 40-60 bucks. And everyone that has a co2 system should have a release valve. They cost less then 10 bucks, they fit into any tee. You can buy adjustable ones or set ones. I have a 40psi on all my systems. At 41psi, the valve opens and vents. It has never happened, but every system should have one.


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## jeffkrol (Jun 5, 2013)

cwnannwn said:


> Wow, 200 bucks for a regulator. Dang. I always have gone with the cheaper co2 regulators from brew and soda stores. The are two stages, one reduces tank pressure down to 40-120psi and the next reduces it down to what you set it to. They cost 40-60 bucks. And everyone that has a co2 system should have a release valve. They cost less then 10 bucks, they fit into any tee. You can buy adjustable ones or set ones.


Ohh....soo close.. 
They sell 2 "gauge" regulators for $40..
advertising and wording gets tricky.. 
would love to be proven wrong..but...


> I have a 40psi on all my systems. At 41psi, the valve opens and vents. It has never happened, but every system should have one.


NOW THAT is something that is very often neglected..
Reg. are protected from over-pressure from the tank but nothing protects downsteam things from over-pressure..
Ones I used were like this..
https://www.amazon.com/Control-Devi...&sr=1-1&keywords=60+psi+pressure+relief+valve

On a hard plumbed tee..
What do you use?


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## leaf (Jun 27, 2009)

deepgreen1 said:


> Your idea about using two single stage regulators is interesting indeed. Do you know whether there is a minimum required inlet pressure?


I could not find any information on minimum safe working pressure but from my experience with air systems it is a thing. I feel it is the primary reason for tank dump, and why regs of higher quality with better machining and tolerances minimize but not completely negate this effect. I believe this is why you should use a two stage, because the low pressure regulator has safe working ranges that covers everything we do in the aquaria.


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