# CO2: Single stage vs. Dual stage regulators



## AlecFish (Nov 26, 2011)

What are the differences between both, I'm contemplating between the two. I'd like to know the advantages and disadvantages of both and find what the better option will be for me. 

*This will be for a 75 gallon


Thanks!


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## Doc7 (Apr 7, 2011)

Dual stage steps down the incoming cylinder pressure to an intermediate, regulated pressure for the 2nd stage to deal with and step down to your desired working pressure.

The impact of this for your purposes is that you will have consistent CO2 until your tank is nearly empty, at which point flow will stop. Some single stage regulators MAY experience an "End of tank dump", where low CO2 pressure remaining in the cylinder (when liquid CO2 is all evaporated) causes wild fluctuations in working pressure up to and including dumping all remaining CO2 contents through your system into the tank.


A main advantage/disadvantage is the difference in pricing.


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## AlecFish (Nov 26, 2011)

Price wise, what are the differences?


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## maknwar (Aug 10, 2008)

Depends. Sometimes you can find a dual stage cheaper than a single stage.

New regulators, the pricing is huge or hundreds. Go with a nice used dual stage and you will never regret it.


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## proaudio55 (Oct 20, 2011)

I can't let this thread go without posting my epic regulator :wink:

This pic lets you visualize exactly what's going on inside a multi-stage regulator. 800PSI on the tank --> first step down pressure regulator --> second step down pressure regulator --> and this one includes a third step down just for kicks 

EOTD worry warts: Meet your God! LOL @ DIY Regulator









http://www.plantedtank.net/forums/pHosting/f/9113_EOTD3c.jpg


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## Relativistic (Mar 5, 2012)

> http://www.plantedtank.net/forums/pHosting/f/9113_EOTD3c.jpg


Epic regulator is epic! :icon_lol:


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## carpalstunna (Mar 22, 2012)

ok but if on a dual stage the output was preset to say 30psi wouldnt the main tank have to get down close to that before it would slip? Or would it be sooner. Seems you could just keep an eye on the tank psi and when it began to drop refill it.


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## Doc7 (Apr 7, 2011)

That's exactly what you need to do (drop in pressure from 800-900, temp-dependent, means all liquid is gone.). Alternatively you can weigh the cylinder occasionally and compare weight vs empty to know when you're close.

The problem is, if you use a decent amount and dependent upon tank size, it could run out of liquid and enter the "dropping gas pressure" phase and do an end of tank dump before you even noticed what was happening.

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## y84k (May 31, 2007)

Aquarist14 said:


> Price wise, what are the differences?


I have to put in a plug for maknwar and bettatail here... If you really wanna do it right and don't mind a little DIY on your end buy a nice used dual stage reg from maknwar and get a post body set-up from bettatail like I did recently... They are both more than willing to help and answer any questions that may arise and you will end up with a very nice quality set up in the end. I wanna say I ended up spending around $150 but that included the dual stage reg, cga-320 fitting, post body kit, needle valve, clippard mouse solenoid, bubble counter, check valve for bubble counter, and the co2 tubing. The only thing I had to add to the system was to go pick up a co2 tank and put in a little research on how to put it all together and get it up and running.


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## hbosman (Oct 5, 2006)

I've used dual stage regulators for about two years. When I used to use single stage, I would simply tweak the working pressure down daily, as it rose. This happens when there isn't liquid CO2 left in the cylinder. I would do this for the final week before the cylinder needed a refill. If I would have known that once the liquid is gone, that there is only 15 % CO2 left by volume, I wouldn't have bothered and swapped the tank as soon as the working pressure needle rose. Anyway, I bought two Dual stage regulators from Ebay for $55.00 so, I can now run the cylinder empty without tweaking. That's really the difference in usage. Single stage regulators you might have to tweak as it empties, or swap the cylinder before its empty. Dual stage, you can run it empty without tweaking it. Dual stage can be bought used for about the price of a single stage but, requires some DIY and research. I've never experienced an "End of Tank Dump". I suppose this could happen if the working pressure rose with a really crappy needle valve. But I think in most cases, this happens when the user doesn't notice the change in that final week.


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## btimmer92 (Mar 12, 2011)

actually, needle valves have no impact on the end of tank dump. The main difference between needle valves is the level of precision of the turns.

And aquarist14, if you need a post body, I will be glad to supply you with one. Check the link below


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## AlecFish (Nov 26, 2011)

y84k said:


> I have to put in a plug for maknwar and bettatail here... If you really wanna do it right and don't mind a little DIY on your end buy a nice used dual stage reg from maknwar and get a post body set-up from bettatail like I did recently... They are both more than willing to help and answer any questions that may arise and you will end up with a very nice quality set up in the end. I wanna say I ended up spending around $150 but that included the dual stage reg, cga-320 fitting, post body kit, needle valve, clippard mouse solenoid, bubble counter, check valve for bubble counter, and the co2 tubing. The only thing I had to add to the system was to go pick up a co2 tank and put in a little research on how to put it all together and get it up and running.


That's exactly the amount of money that I want to be spending and I don't mind doing a little to get it going. 

Couple questions

What does the post body do?

What size tank (lbs) should I be getting? is a paintball tank to small


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## oldpunk78 (Nov 1, 2008)

Post body = all the stuff coming off the reg body. Ie:

pipe fittings, solenoid, needle valve, ect...

A #10 tank would be great. A #5 at minimum. Paintball is too small for a 75.


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## y84k (May 31, 2007)

Aquarist14 said:


> That's exactly the amount of money that I want to be spending and I don't mind doing a little to get it going.
> 
> Couple questions
> 
> ...


I have a 5lb mainly because that size fits under my aquarium in the cabinet stand perfectly.

A post body kit is everything that is attached to the regulator on the outtake side. So your manifold, needle valve, etc. 

Also I forgot to mention one other thing you will need is a a way to get the co2 into your aquarium. After a bunch of research I built a cerges reactor (something you can research here on the forum)


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## samamorgan (Dec 31, 2011)

Rule of thumb for tank size: largest possible tank you can fit under your stand with the regulator attached.


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## exv152 (Jun 8, 2009)

^^agree with all the suggestions above. I use a single stage reg and keep an eye on it daily, by checking the working pressure, cylinder pressure etc. So I don't really see the need for a dual, but if you can get one for the price of a single, go for it. Otherwise I can't justify spending upwards of $250. As for the tank itself, the bigger the better, especially with a 75g if you were to go with a 5lbs tank you may be refilling every 3 months. So I'd say min go for a 10. But consider the space you have in your cabinet first because I have a 10 lbs tank and it measure 20 inches in height without the reg.


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## AlecFish (Nov 26, 2011)

y84k said:


> I have a 5lb mainly because that size fits under my aquarium in the cabinet stand perfectly.
> 
> A post body kit is everything that is attached to the regulator on the outtake side. So your manifold, needle valve, etc.
> 
> ...


I've done some research beforehand and I will most likely get an atomic inline diffuser. They work just as well as a reactor and take up a fraction of the space. 

Also would this be considered a single stage or a dual? 
http://www.amazon.com/Milwaukee-Instruments-Solenoid-Regulator-Counter/dp/B001DTNWF2/ref=sr_1_1?ie=UTF8&qid=1334862221&sr=8-1

This one is just an idea. 

Any recommendations for a single or a dual stage regulator for under $100, on ebay or SnS?


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## carpalstunna (Mar 22, 2012)

arent going to find a dual stage for under a hundred probably at least not with everything. That milwaukee is a single stage. that and the aquatek ones are popular entry level options.


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## AlecFish (Nov 26, 2011)

Overall, in quality is the Aquatek better than the Milwaukee. I've heard mixed reviews of the Aquatek due to the preset working pressure, but I'm still not definite.


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