# How important is a dual stage CO2 regulator?



## oscarlloydjohn (Dec 3, 2017)

I'm looking to set up a CO2 system using sodastream bottles (It seems like a good medium between disposable systems and full size systems). Do I need a dual stage regulator to prevent end of tank dump? Single stage ones are much cheaper and was wondering if I could get away with using one but not killing my fish. My tank is 30L so the CO2 bottle should last a while. Here are the single stage and dual stage regulators I've been looking at. https://www.co2supermarket.co.uk/co...enoid-magnetic-valve-vertical-valves-p15.html https://www.co2art.co.uk/collection...dual-stage-regulator-with-integrated-solenoid Would the single stage one be appropriate? I'm planning to use an inline diffuser if that makes a difference. Thanks


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## Surf (Jun 13, 2017)

Two stage regulator setup prevents the output pressure of the regulator from increasing as the pressure in the storage bottle drops. The pressure increases of the output is generally a percentage of the pressure drop in the storage bottle. Since the pressure in the storage bottle is often close to 1000psi. a 300psi or larger drop can result in a significant increase in output pressure. in some cases this results in what people call an end of tank dump that can significantly increase CO2 levels in the tank and might kill your fish. 

Adding a second regulator greatly reduces the effect. The first regulator can be set at 60 PSI. As the bottle pressure drops the output pressure will increase somewhat. but the pressure increase will likely be less (probably much less) than 100psi. The second regulator will not see the bottle pressure. The second regulator will have a much smaller change in output and you likely would not ever see a end of tank dump.

A company like Swagelok that makes regulators should tall you how big of a pressure increase you will see for any regulator they make. Some have a bigger increase than others. However most companies will only buy generic regulators and relabel them and then sell them. These resellers cannot provide you with this information. Buying an expensive "quality regulator" is no guarantee that you will not see and end of tank dump. Also when some re sellers say dual stage they may actually be referring to the two pressure gauges on the regulator instead of ones with two internal regulators (which would cost more than a simple single stage regulator). Looking at your links I cannot tell with any confidence what type of regulators these are.


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## Nubster (Aug 9, 2011)

Depends on who you ask...lol...big can o'worms here. Some believe that EOTD is rare, possibly even mythical and non-existent. Others thinks it's a common occurrence and will happen to anyone that uses a single stage regulator. Then there's the camp that is somewhere in between. I'm in that group. I think it can and does happen. I don't think it happens that often. I think it happens more than would be considered a rare occurrence but less than one would call being a problem. 

IMO, for the price of one of the expensive single stage regs, you can build a better quality dual reg. That's the route I'm taking. I'll be in for $200 and arguably have a better regulator that you can get from someplace like GLA for the same price or more. I personally think that the needle valve is more important than worrying about single or dual stage...needle creep happens with cheap parts and they are more difficult to adjust as well.


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## oscarlloydjohn (Dec 3, 2017)

Nubster said:


> IMO, for the price of one of the expensive single stage regs, you can build a better quality dual reg. That's the route I'm taking. I'll be in for $200 and arguably have a better regulator that you can get from someplace like GLA for the same price or more. I personally think that the needle valve is more important than worrying about single or dual stage...needle creep happens with cheap parts and they are more difficult to adjust as well.


So do you think I would be ok with a single stage then provided I refill the tank before it's fully empty? The single stage with solenoid from CO2supermarket is pretty affordable but I don't know whether the lower price is worth the risk of EOTD. There's so much different info out there!


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## Nubster (Aug 9, 2011)

Yeah...you'd be pretty safe if you could refill before the tank was empty...problem being that it's hard to know or catch before it runs empty of liquid.

I was back and forth myself, I could either cheap out and spend around $100 on a single stage regulator with mostly good reviews or just pony up and spend $200 but have peace of mind that I won't have any issues with EOTD and using high quality parts, the regulator _should_ last me many years.

Like I said...this is a bit of a hot topic with strong opinions...I'm sure there will be some other thoughts added soon.


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## Maryland Guppy (Dec 6, 2014)

oscarlloydjohn said:


> So do you think I would be ok with a single stage then provided I refill the tank before it's fully empty? The single stage with solenoid from CO2supermarket is pretty affordable but I don't know whether the lower price is worth the risk of EOTD. There's so much different info out there!


When you notice a decrease in tank pressure, this meaning the normal 850 or so PSI starts to drop you have run out of liquid CO2 and are running on gas only.
If your tank is in plain view and you look @ it everyday this is your sign to get it filled.
Waiting to long "could" create an EOTD but not always.

What type of diffusing method or working pressure will you require?


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## oscarlloydjohn (Dec 3, 2017)

Maryland Guppy said:


> What type of diffusing method or working pressure will you require?


I could use an inline diffuser or one in the tank. Someone said that inline diffusers need a higher pressure though. Would the working pressure of a single stage be enough? Maybe I would have to get a dual stage if I wanted to use the inline one

Bump:


Nubster said:


> Like I said...this is a bit of a hot topic with strong opinions...I'm sure there will be some other thoughts added soon.


I appreciate the help


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## Maryland Guppy (Dec 6, 2014)

oscarlloydjohn said:


> I could use an inline diffuser or one in the tank. Someone said that inline diffusers need a higher pressure though. Would the working pressure of a single stage be enough? Maybe I would have to get a dual stage if I wanted to use the inline one


A single or dual stage would be able to deliver the same working PSI.


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## houseofcards (Mar 21, 2009)

I'll put this is layman's term. 

This is a picture of my EOTD Popcorn. 










Every time someone here has a valid EOTD (not needle valve creep) as described by @Nubster using a single stage regulator I eat some of the popcorn. As you can see I really haven't eaten any of it and it's several years old. I hope that puts things in perspective.


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## MCFC (Feb 12, 2017)

I've seen a lot of people warning about EOTD but I've yet to read about anyone who can say for certain it happened to them. For what it's worth, I use 2 different cheap single-stage regulators, I let my CO2 fully empty every time, and I've had no issues (anecdotal evidence FTW?). I think it's equally as likely that Big Foot and Nessie will come through the door and eat your fish and plants as it is to see EOTD.


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## oscarlloydjohn (Dec 3, 2017)

Lol, thanks for clearing things up everyone


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