# GLA CO2, two stage necessary?



## jeffkrol (Jun 5, 2013)

Little Soprano said:


> I'm asking for a new CO2 regulator for christmas, as my old one, isn't exactly ideal for planted tanks, and is better suited to a ceramic diffuser-type simple setup. I'll probably use it on my 10 gallon actually. It's a Blueprint single stage regulator set-up, thats meant for a Grow-House set-up. It's actually been incredibly reliable, and is set it and forget it, but I have no way of setting or knowing the working pressure, and while it worked great on my 40, I want something thats more accurate for the new tank.
> 
> I was looking at GLA, and was thinking of the stainless steel regulator, but is it worth the extra $200.00 for a two stage regulator? Checking my tank pressure has become a daily habit for me over the last 18 months. Plus I typically pick up the tank and if it's very light I'll weigh it to get a better idea of how much is left.


Even buying new you can save a few hundred dollars doing it yourself...
SS is a cosmetic choice..

Smith Oxygen Regulator - 2 Stage 30 Series

Addendum : Retail hoke 1 degree 1/4npt metering valve:
http://catalog.circlevalve.com/item/hoke-metering-valves/hoke-milli-mite-1300-series/1335m4b?


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## rdmustang1 (Oct 20, 2013)

Dual stage helps prevent end of tank dumps where extra CO2 is dumped into your aquarium when the tank is low. It's basically an insurance policy. Some people say that it has happened to them. Others have said they use single stage regulators and have never seen it happen. Have you been using your single stage regulator for a long time and if so have you ever had a dump at the end of a tank?


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## oldpunk78 (Nov 1, 2008)

The really expensive, 2-stage from gla is completely nessisary. You'll kill all your fish with out it. 



Jk, as far as I'm concerned, it's just a status symble like a Mercedes.


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## Paxx (Dec 17, 2012)

I've used the GLA "Gro" (although it was called "Primo" when I bought it, iirc) since 2012 on my 55g. I use a standard glass ceramic diffuser at about 10psi working pressure. Aside from some bad CO2tank/regulator washers a few months ago the performance and reliability have been superb. The washers were my bad.

It has been my experience that if you refill your CO2 tank once it hits the "red zone" on the CO2 tank gauge, you'll have little to worry about as far as EOTD is concerned. 

If however, the you let the CO2 tank empty nearly completely you may or may not get a EOTD with this particular setup. I say may or may not because the three times I have let it run down to zero on purpose (while monitoring) it did EOTD once. The only other EOTD I have experienced with this gear was related to the bad washer leaking out overnight after a refill and a slight EOTD the next day before I noticed the problem.

For me refilling when I hit the red zone pretty much makes EOTD a none issue with this regulator setup.


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## Centromochlus (May 19, 2008)

I've owned both single-stage and dual-stage regulators (all from GLA) and i honestly haven't been able to tell the difference. A single-stage regulator is fine for most hobbyists.


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## Little Soprano (Mar 13, 2014)

I was thinking the SS, since it's next to my sump and it does evaporate quite a bit (no lid yet), and I want to protect it from the potential to rust is all, plus I figure it will last longer due to the longevity of SS. 

I've used a single stage for a year and a half. Never had an end of tank dump, when I feel like the tank is getting low, since CO2 is cheap, I'll weigh it and if less then a pound is left, I go exchange it for a full one. Which on the 40 was about 18 months with a 20lb tank.


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## shrimpNewbie (May 6, 2011)

oldpunk78 said:


> The really expensive, 2-stage from gla is completely nessisary. You'll kill all your fish with out it.
> 
> 
> 
> Jk, as far as I'm concerned, it's just a status symble like a Mercedes.


Agreed, your dual stage I purchased years ago was the only dual stage I've used, I've attempted many times to cause eotd and have come to the conclusion it is just something someone blamed for the sudden death of their fish. I purely use single stage unless I'm going for a nice looking under tank system which I did and will do with steel stands.

Completely safe buying a single stage.

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## Argus (May 22, 2013)

GLA claims their single stage regulators are protected against end of tank dumps. I have the GLA PRO-2 setup, but haven't emptied a tank yet. I've never seen a review of GLA regulators claiming an end of tank dump. I've seen lots of reviews of Aquatek regulators claiming EofTD.


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## jeffkrol (Jun 5, 2013)

It is what it is...



> 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.













see one of the problems is if you are running on the cusp to begin with. ANY variation could be fatal... 

The Basics of Pressure Regulators | www.beswick.com

That said , for the more creative, running 2 single stages in series is just as good and usually cheaper..

considering I'm inherently lazy, I opted for a 2 stage that I run dry all the time.. Never killed anything BUT I also don't max my CO2 to the short of choking fish point..


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## AlanLe (Jan 10, 2013)

I would opt in for a dual stage reg. Single stage is fine but you have to refill the tank right away when it's near empty. It's like a time bomb.


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## latchdan (Sep 7, 2007)

I had a Azoo Regulator that I bought a long time ago. I would get something I called End of Tank dump, (it may not of been). This reg you couldn't adjust the working pressure. Near the end of the Co2 tank the working pressure would double, which would increase the amount of co2 being injected. I came home a couple times and found my fish gasping. I would either have to reduce the bubble count or swap out the tank.

I now how a dual stage reg, haven't had the same issue with the new reg. It could of been just a cheap single stage that causes this, I'm not sure.


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## shrimpNewbie (May 6, 2011)

AlanLe said:


> I would opt in for a dual stage reg. Single stage is fine but you have to refill the tank right away when it's near empty. It's like a time bomb.


I ran mine to empty never lost fish because of it, spreading fear is irresponsible 

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## bk. (Sep 27, 2014)

shrimpNewbie said:


> I ran mine to empty never lost fish because of it, spreading fear is irresponsible
> 
> Sent from my SM-N910T using Tapatalk


I wouldn't say he is spreading fear. End of tank dump is a true phenomenon and many have experienced loss because of it. End of tank dump from a 5lb canister is going to have a much greater impact on a 20 gallon tank compared to a 125 gallon tank.


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## AlanLe (Jan 10, 2013)

shrimpNewbie said:


> I ran mine to empty never lost fish because of it, spreading fear is irresponsible
> 
> Sent from my SM-N910T using Tapatalk



Not trying to be negative here. There are a lot info and threads on this forum that talk about eotd and single stage reg. We can also read more about this topic here
https://www.mathesongas.com/pdfs/products/Regulators-Product-Line-Overview.pdf


-Alan


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## kevmo911 (Sep 24, 2010)

Remember that pressure rise does happen - it's not some myth. It's just that it's not terribly obvious in all but the cheapest regulators, and generally won't make much, if any, difference. So pressure rise absolutely does happen, in all cases, but EOTD, as it applies to our tanks, is more of a rarity.

According to Victor specs, the HPS270 (single stage) has a less than 0.5 psi delivery pressure increase per 100 psi drop in inlet pressure. So a max of less than 4 psi increase as cylinder pressure nears zero.
The HPT270 (dual stage version) has a less than 0.1 psi increase per 100 psi drop, so a max of less than 1 psi total increase is possible.

Interestingly, the SGS500 and SGT500 both show a delivery rise of <.92 psi per 100 psi drop. I'm wondering if that's a typo. I suspect the SGT500 is actually <.07, the same as the HPT500.

HPS500 (single) is at <.92, and HPT500 (dual) is at <.07

Here's the data sheet this came from:
http://victortechnologies.com/corp_pdfs/56-0874 Victor HPI Catalog.pdf

And here's a vid of a Milwaukee dumping, increasing by about 14 psi:
https://www.youtube.com/watch?v=M08hPs-J3SM


The one thing I don't have any evidence on is whether the decrease scales with working pressure, meaning, would that Milwaukee increase 14 psi from a working pressure of 10, as well as from a working pressure of 71 (as shown)? I *think* it would be the same. *IF* I'm correct, it's generally safer to use a higher working pressure than a lower working pressure. That Milwaukee would have jumped up by 140% if it started at 10, but only 20% if starting from 71.

I've tried, but can't find any data sheets on the Taprite or Cornelius regs that GLA uses (no idea what the industrial reg models are). I suspect they're not quite as good (as far as pressure rise goes) as the standard industrial single stage regs that are all over Evilbay. But they're likely a good bit better than Milwaukee, Aquatek, Azoo, Dici, etc.


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## 691175002 (Apr 28, 2009)

I've been using the same generic brand single stage regulator for >10 years now and always run the tank to empty. Never had a dump.

I think its more a reflection of regulator quality, I don't know of anyone who has experience EOTD with a quality regulator regardless of how many stages it had.


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## shrimpNewbie (May 6, 2011)

bk. said:


> I wouldn't say he is spreading fear. End of tank dump is a true phenomenon and many have experienced loss because of it. End of tank dump from a 5lb canister is going to have a much greater impact on a 20 gallon tank compared to a 125 gallon tank.


A 10-20psi increase in working pressure is hardly worth calling eotd, if you have a decent metering valve the increased flow is negligible at best, I think everyone who looks at a possible eotd completely ignores the fact there is a metering valve. A sudden increase of even 50psi would not cause a massive increase in flow, maybe a bubble or two more per second, a far cry from the eotd theory which is a spontaneous exhaustion of the contents of the tank. Use a good regulator and good metering valve and let's put this eotd to rest. I trust Victor with my fish and have personally tested several of their regulators, the increase is barely noticeable. Even in the cheapest one I tested at 21 bucks on fleabay

Sent from my SM-N910T using Tapatalk


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## shrimpNewbie (May 6, 2011)

latchdan said:


> I had a Azoo Regulator that I bought a long time ago. I would get something I called End of Tank dump, (it may not of been). This reg you couldn't adjust the working pressure. Near the end of the Co2 tank the working pressure would double, which would increase the amount of co2 being injected. I came home a couple times and found my fish gasping. I would either have to reduce the bubble count or swap out the tank.
> 
> I now how a dual stage reg, haven't had the same issue with the new reg. It could of been just a cheap single stage that causes this, I'm not sure.


What you experienced is common with low grade non industrial regulators. The psi does in fact rise but you won't see fish killing flow increase 

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## chinaboy1021 (May 30, 2003)

DUAL STAGE FOR SURE. 

It's $100-$150 extra in cost, but you can feel safe to have a sustainable planted tank for years to come. I had a single stage, there was EOTD...killed half of my fish. No point. It's like buying an aquarium that is likely to crack. Big headache.


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## kevmo911 (Sep 24, 2010)

shrimpNewbie said:


> A 10-20psi increase in working pressure is hardly worth calling eotd, if you have a decent metering valve the increased flow is negligible at best, I think everyone who looks at a possible eotd completely ignores the fact there is a metering valve. A sudden increase of even 50psi would not cause a massive increase in flow, maybe a bubble or two more per second, a far cry from the eotd theory which is a spontaneous exhaustion of the contents of the tank. Use a good regulator and good metering valve and let's put this eotd to rest. I trust Victor with my fish and have personally tested several of their regulators, the increase is barely noticeable. Even in the cheapest one I tested at 21 bucks on fleabay
> 
> Sent from my SM-N910T using Tapatalk


That's not how a metering valve works. A sudden increase of 50 psi would absolutely cause a massive increase in flow, though a diffuser would slow the increase in a way that a reactor wouldn't.

I agree with you that EOTD is much more common in people's minds than in reality, and I agree that a decent industrial regulator should make that worry vanish entirely.

But as somebody who's tested probably 15-20 different models of metering valves, I'm very sure that the valve doesn't limit the increased pressure that way.


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## prototyp3 (Dec 5, 2007)

shrimpNewbie said:


> What you experienced is common with low grade non industrial regulators.


That's what I'm thinking too. I never had a problem using a reasonable quality single stage regulator running reasonable rates of CO2 injection. 

My theory on the matter? I think people ride the line too close to suffocating their tank inhabitants during normal operation. Then when a fluctuation (even slight) occurs it looks like an *end of tank dump disaster *to them. A lot of people openly admit their plants and scapes are the priority, and fish are more of an afterthought. I'm often shocked to see some of the bubble rates people run.


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## Little Soprano (Mar 13, 2014)

prototyp3 said:


> That's what I'm thinking too. I never had a problem using a reasonable quality single stage regulator running reasonable rates of CO2 injection.
> 
> My theory on the matter? I think people ride the line too close to suffocating their tank inhabitants during normal operation. Then when a fluctuation (even slight) occurs it looks like an *end of tank dump disaster *to them. A lot of people openly admit their plants and scapes are the priority, and fish are more of an afterthought. I'm often shocked to see some of the bubble rates people run.


I always ran my CO2 at just enough for the plants to be happy. The fish are the priority for me, the plants are FOR the fish in the end. But I guess to me, I used a budget Blueprint CO2 regulator. While it's been reliable as hell, it's a hydroponic/grow house regulator. It's meant to do a whole room. Great GREAT needle valve, and the solenoid has worked great as well, but it has no bubble counter (which is why I use a built in one on my diffuser), and it has no working pressure gauge, which I need to go to a reactor or diffuser. 

I do see the benefits of a two stage regulator (this discussion has been very informative), but is it necessary if you keep a close eye on your tank level? I always check mine, and always checked on the weight of the tank as well as the pressure. My refill place is 5 minutes down the road, so getting it refilled is no big deal to me, plus all I do is just exchange the tank, so it's easy easy for me to get more. If I have less then a pound (weigh on scale), then it's refill time. $8.00 is not breaking the bank.

I guess I've just never let my CO2 get to a point that I have an end of tank dump.


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## Jeff5614 (Dec 29, 2005)

shrimpNewbie said:


> A 10-20psi increase in working pressure is hardly worth calling eotd, if you have a decent metering valve the increased flow is negligible at best, I think everyone who looks at a possible eotd completely ignores the fact there is a metering valve. A sudden increase of even 50psi would not cause a massive increase in flow, maybe a bubble or two more per second, a far cry from the eotd theory which is a spontaneous exhaustion of the contents of the tank. Use a good regulator and good metering valve and let's put this eotd to rest. I trust Victor with my fish and have personally tested several of their regulators, the increase is barely noticeable. Even in the cheapest one I tested at 21 bucks on fleabay
> 
> Sent from my SM-N910T using Tapatalk


Increasing your working pressure by 10-20 psi is going to significantly increase your bubble count no matter what needle valve you have. Try increasing your working pressure from 20-40 psi without adjusting your needle valve and seen how it goes.


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## shrimpNewbie (May 6, 2011)

prototyp3 said:


> That's what I'm thinking too. I never had a problem using a reasonable quality single stage regulator running reasonable rates of CO2 injection.
> 
> My theory on the matter? I think people ride the line too close to suffocating their tank inhabitants during normal operation. Then when a fluctuation (even slight) occurs it looks like an *end of tank dump disaster *to them. A lot of people openly admit their plants and scapes are the priority, and fish are more of an afterthought. I'm often shocked to see some of the bubble rates people run.


Indeed, I guess the main reason I never ran into an issue is I'm conservative with injection I only raise it if there is a sudden bloom of algae under the same lights

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