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Pressurized CO2...Just thought I'd share.

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So, there have been a lot of threads (it seems) lately regarding pressurized CO2. Hopefully, this primer will help alleviate any fears that people have when starting to delve into CO2 as it can be quite intimidating at first. In addition, hopefully this primer will answer some of the most commonly asked questions regarding pressurized CO2.

As this thread will be discussing how to set up a pressurized CO2 system, advantages/disadvantages of using a pressurized setup versus a DIY (yeast) CO2 system will not be discussed in this primer. For more information, please take a look here:

http://www.plantedtank.net/forums/9-general-planted-tank-discussion/107303-newbie-setup.html#5

On to pressurized CO2!

First, when people refer to pressurized CO2, we often read that we will need a "regulator" or a "regulator build." What does this mean exactly? This term is thrown around quite loosely in the aquarium hobby, but a pressurized CO2 system consists of more than just a regulator.

Here are the essential components you will need:

1) A CO2 cylinder
CO2 cylinders come in various sizes. They are often used in paintball guns (usually sold as 20 oz cans). They also come in 2.5, 5, 10 and 20 lb sizes (larger sizes such as 50 lb tanks do exist, but they are quite large and bulky, and are not commonly sold outside of specialty applications).

CO2 tanks come with a fitting known as a CGA320 fitting, which is standard in North America. Europe and Asia use different industrial standards. Paintball tanks, however, do not come with this fitting, and come with a pin depression type valve. More on this will follow below.

Many people believe that getting a small, paintball CO2 tank is "cheaper", however, this is not usually the case. Regulators (see below) often come with CGA320 fittings (or can be adapted to such). However, as paintball tanks do not contain this CGA320 fitting, normal regulators cannot be used, and you must purchase either a special regulator with the required fitting, or look around for a paintball tank to CGA320 adapter (often, quite difficult to find). In addition, refill costs for CO2 tanks are generally not much different. The refill cost for (say) a 5 lb tank and 10 lb tank may only be a few dollars different. For example, I can get my 10 lb tank refilled for $17.50, while a 20 oz paintball tank may cost $5 to refill. This means that the cost per pound of gas is more for a smaller tank. In addition, the larger the CO2 tank, the longer you can go without refilling the tank, etc. It can be quite a hassle to drive out and refill the tank, depending on where you live. The general piece of advice is to get the largest tank that you can afford and/or is feasible for the space that you have.
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So what would be a ballpark rate for a 75 gallon tank? My plans are to plant a carpet (Monte carlo) and anubias, maybe some swords. At the moment I don't have my local water quality scores sitting in front of me, but there's got to be a relationship between rate of CO2 injection and volume of water. I'm trying to figure out what an appropriately sized system would be so I don't have to re-purchase different parts down the road. Again, the information on this site is very much appreciated.


Thanks!
 

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The next piece of equipment that is essential is the needle/metering valve.

A needle valve is a piece of equipment that takes the delivery pressure of the regulator and further drops the pressure down to the very fine flow rate that we require for aquarium purposes (i.e. we often refer to our flow rates as "bubbles per second"). A metering valve is the "high end" needle valve.

Needle valves work by restricting the flow of gas via a small needle (hence the name) that can be opened/closed via a screw/caliper handle. In general, higher quality needle valves/metering valves will have allow finer control by having more threads. This means that it takes more turns of the handle to change the flow of CO2, meaning you get finer resolution (i.e. if you turn a needle valve 1 turn and get an increase from 1 bubble per second to 10 bubbles per second, you would have a hard time adjusting your flow. However, if you turn another needle valve 1 turn and only get an increase from 1 bubble to 2 bubbles per second, you can achieve much finer control).

A good quality needle/metering valve is essential. This is definitely one piece of equipment you do not want to be stingy on.

Here are some brands that I recommend:
Fabco (particularly the NV55)*
Ideal (particularly the 52-1-11)**
Swagelok (many various models available)
Parker (also many various models available)

For those that are more technically inclined, have a look at the thread over at the Barr Report (linked above), as it discusses the finer points of a quality needle/metering valve (i.e. best Cv to look for, etc)

One brand of needle valve that I would strongly advise against is the Clippard needle valve (Part #: MNV-4K2) . While it is quite cheap (perhaps $18, if ordered online), many users have lamented that the quality of this particular needle valve leaves much to be desired. A common problem with this needle valve is that it "floats." This means that while you set the CO2 flow rate to a particular setting one day, the next day (or perhaps within a few hours!), the CO2 flow rate will change noticeably, requiring more fiddling on your part. This means that while you set your CO2 to an "optimal" flow rate one day, the flow might stop the next day, or it might be so high that it will gas all your fish to death. Definitely, this is something you want to avoid, so do not be stingy on a quality needle valve.

*Note 1: The Fabco NV55 contains #10/32 port fittings. These are not your standard fittings and adapters cannot be purchased at the hardware store. The setup I would recommend is to have #10/32 to hose barb fittings and not trying to find #10/32 to (say) 1/8" NPT adapters. This is because attempting to attach the Fabco NV55 to the regulator is not a good idea. The Fabco NV55 is quite a heavy needle valve, and the #10/32 fittings are quite small and fragile, so a slight bump may cause the fitting to break. With the hose barb adapters, you can run this needle valve in-line.

**Note 2: This particular Ideal metering valve has 1/8" female NPT ports on both ends. Other models exist, and I can also forward you the PDF/website with the particular details if you require/PM me.
Is there a rule of thumb for how much CO2 flow in SCFH or SCFM is required to keep a given volume of water at the proper level of CO2 (in ppm)? One online calculator recommends 25ppm of CO2 for a tank with a medium amount of plants. I'm guessing there are too many variables (water temperature, surface agitation, type of plants, photo period, water hardness, etc) to give an accurate figure, but what about an average range? If the volume of a bubble is approximately 0.001 cubic inches (complete guess here), then 2 bubbles per second is only 0.00007 SCFM. I'm wondering why some have had to use pressures of up to 45 psi to get this small of a flow rate. Their needle valves must be super restrictive.
 

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Discussion Starter · #405 ·
Is there a rule of thumb for how much CO2 flow in SCFH or SCFM is required to keep a given volume of water at the proper level of CO2 (in ppm)? One online calculator recommends 25ppm of CO2 for a tank with a medium amount of plants. I'm guessing there are too many variables (water temperature, surface agitation, type of plants, photo period, water hardness, etc) to give an accurate figure, but what about an average range? If the volume of a bubble is approximately 0.001 cubic inches (complete guess here), then 2 bubbles per second is only 0.00007 SCFM. I'm wondering why some have had to use pressures of up to 45 psi to get this small of a flow rate. Their needle valves must be super restrictive.
The 45 PSI that some people are using is because of the ceramic disc/glass diffuser that are used. The pores are tiny, and require quite a bit of pressure before CO2 can be forced out.
 

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Just wanted to share some information I learned of while shopping around for flexible tubing on McMaster-Carr. A lot of the tubing has a maximum pressure rating under 50 psi. Some are rated as little as 10 psi, a bunch at 20 and 30 psi, and only a few over 50 psi. Also, some say they are not for use in water, so for those of us using in-tank diffusers, we need to ensure the tubing can be in constant contact with water. I'll post back once I learn more and provide some part numbers of appropriate tubing for pressurized CO2 applications.
 

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Thank you, Darkblade48 for your excellent information. I have referenced this thread repeatedly as I began to re-enter the hobby with some better equipment (specifically, non-DIY CO2).

I ended up with a Victor Regulator G150-60-320, a Clippard solenoid MME-2PDS-D110, some plumbing pieces from Amazon & Lowe's, and a pair of Dwyer flow meters RMA-151-SSV to meter the flow to two separate tanks.

In addition, I have nylon check valves, in-tank diffusers which also act as bubble counters, and drop checkers in each tank.

I originally bought a cheaper regulator + solenoid + needle valve + bubble counter kit that was a complete disaster from the moment I felt the weight of it (lack thereof). Thankfully, Amazon makes returns easy. Finding better gear is a little bit more work (and $$), and you won't get free next-day delivery, but it's worth it.
 

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THANK YOU Darkblade48 for the excellent information!


I was wondering, around 10 years have passed since the first post...with the advent of Amazon, fleabay etc, I see lots of cheap carbon dioxide "kits" for aquarium use. Some are only 40 bucks complete. But like whatever else in life, you get what you pay for.... so I have two questions:


1. Is the equipment recommended in the first few posts still relevant or newer models are available?
2. Are there any cheaper "equivalents" out there which are reasonable in reliability?


Also, From time to time I see people selling beer making equipment, which has a CO2 cylinder and some sort of regulator which looks kinda similar to the photos here. Is that worth looking into?
 

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Thanks again for the good info,


Although I am pretty sure everyone here already knows this info.....I just wanted to add that there is a newer model of the Fabco NV55 called Fabco NV-55-18. It is supposed to make it easier to mount straight to the regulator.


https://www.fabco-air.com/products/flow_controls/NV-55-18.html




The next piece of equipment that is essential is the needle/metering valve.

snip


Here are some brands that I recommend:
Fabco (particularly the NV55)*


snip


*Note 1: The Fabco NV55 contains #10/32 port fittings. These are not your standard fittings and adapters cannot be purchased at the hardware store. The setup I would recommend is to have #10/32 to hose barb fittings and not trying to find #10/32 to (say) 1/8" NPT adapters. This is because attempting to attach the Fabco NV55 to the regulator is not a good idea. The Fabco NV55 is quite a heavy needle valve, and the #10/32 fittings are quite small and fragile, so a slight bump may cause the fitting to break. With the hose barb adapters, you can run this needle valve in-line.
 

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Discussion Starter · #411 ·
THANK YOU Darkblade48 for the excellent information!


I was wondering, around 10 years have passed since the first post...with the advent of Amazon, fleabay etc, I see lots of cheap carbon dioxide "kits" for aquarium use. Some are only 40 bucks complete. But like whatever else in life, you get what you pay for.... so I have two questions:


1. Is the equipment recommended in the first few posts still relevant or newer models are available?
2. Are there any cheaper "equivalents" out there which are reasonable in reliability?


Also, From time to time I see people selling beer making equipment, which has a CO2 cylinder and some sort of regulator which looks kinda similar to the photos here. Is that worth looking into?
There definitely is newer equipment that is out there these days, probably with quite competitive pricing. This is simply due to the the supply matching the demand. 10 years ago, there was simply not so much knowledge about pressurized CO2, and I had wrote the primer with the aim to demystify the fog around it.


Regarding cheaper equivalents, some may be better than others. I remember back in the day when I wrote this primer, the only commercially available unit was the Milwaukee MA957, which was not great, to say the least. Since demand was low back then, you could easily find industrial parts online (sold at liquidation prices, to boot), and build a much better setup for a fraction of the cost.


That being said, the primer is in need of an update, so I'll take some time to look into it and update it with some newer parts.


As you mentioned in your other post, the NV-55 (with its problematic fragile #10/32 ports) has been superseded by the NV-55-18, with the 1/8" NPT ports. This is generally what I recommend nowadays, since it's a fairly cheap, ~$30 (last I checked) needle valve.
 

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just bought a 20 lbs. for my 55 gallon. Any idea how long it'll last my newly planted aquarium.

Bump: just bought a 20 lbs. for my 55 gallon. Any idea how long it'll last my newly planted aquarium.

Bump: Is co2art a quality brand?

Bump:
The next piece of essential equipment we will require for a pressurized CO2 setup is the regulator.

A regulator takes the tank pressure of the CO2 tank (normally at ~850 PSI or more, depending on the ambient temperature) and reduces it to a lower pressure.

We normally look for a regulator with two gauges. This means there are two pressure dials. The first pressure dial (high pressure dial) will indicate the pressure in the CO2 tank (i.e. the amount of CO2 that is remaining in the tank). The second pressure dial (low pressure dial, also known as the delivery pressure), will be the pressure that the regulator is bringing the CO2 down to. This is usually set anywhere from 5-20 PSI, depending on the size of your tank, and the desired bubble rate.

Sometimes, we also here the term dual stage used. Note that dual stage and dual gauge are not the same. These terms are sometimes used interchangeably, but this is incorrect. Dual stage refers to an additional body within the regulator that allows the pressure to be dropped in two stages, hence the name. Here are two figures that show the differences between the two:

Single stage regulator:


Dual stage regulator:


As the finer details are beyond the scope of this primer, more information regarding the differences can be found over at the Barr Report, where Left C and I are quite active as well.

http://www.barrreport.com/showthread.php/6470-Dual-Stage-Regulators

There has been a lot of debate over whether a single stage regulator or a dual stage regulator is best. There are often stories about people encountering "end of tank dump" (when the CO2 tank pressure begins to drop, there is sometimes a phenomenon in which all the CO2 will suddenly rush out of the tank, ending up in your aquarium and subsequently gassing all your fish to death) when using a single stage regulator. Some people will blame this on the regulator, while others will point out that it was a combination of a single stage regulator and a poor needle valve. Yet others will point out that despite having a single stage regulator and a sub-standard needle valve, they have yet to encounter "end of tank dump".

In the end, whether you purchase a single or dual stage regulator is up to you; dual stage regulators are the "premium" regulators, and will work reliably for our purposes. Single stage regulators will also work well for our purposes, and are often cheaper than dual stage regulators (more on this later).

Some good brands that I recommend:

Single stage regulators:
Cornelius
Micromatic
Victor

Dual stage regulators:
Concoa
Matheson
Victor

Finally, when purchasing your CO2 regulator, regardless whether it is a single or a dual stage regulator, be sure that you have the correct fitting (CGA320), or else it will not fit the CO2 tank. Sometimes, you may be able to find cheap regulators on eBay (more on this below) that do not have the correct fitting (most commonly found are those with a CGA580 fitting, used for nitrogen ). If this is the case, you can take off the fitting and replace with the appropriate CGA320 fitting.
 

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Bump: Is co2art a quality brand?
I have the CO2Art Pro-SE and the CO2Art Pro-Elite. Of the two I prefer the Pro-Elite. It is easier to fine tune the needle valve, but they both seem to work great and I have them both in use today.
 
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