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Old 02-03-2010, 08:57 PM   #1
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Default Pressurized CO2: How to Guide

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:

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 pieces of equipment 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. 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.

Here are some popular CO2 tank sources, as well as their contact information:

155 Signet Drive
North York, Ontario
M9L 1W9
Tel: (416) 745-1304

Norwood Fire Extinguisher Co
62 Advance Rd
Etobicoke ON, M8Z 2T7
Phone #: 416-239-7357
Fax: (416) 745-6844

Hydrotech Hydroponics (2 locations)
Scarborough Location
2434 Kingston Road
Toronto, Ontario

Markham Location
66 Bullock Drive, Unit 1
Markham, Ontario

Herbert Williams
70 Ironside Crescent, Unit 1, 2 & 3
Scarborough, Ontario
M1X 1G4

Dry Ice & Gases
26 Dorchester Ave,
Toronto, Ontario
M8Z 4W3
(416) 252-7137

Premium Fire Protection
1773 Bayly Street
Unit #10
Pickering, ON
L1W 2Y7

Regarding the pricing, I have found that Norwood has the cheapest pricing on CO2 tanks.

Updated: A 10 lb at Norwood is $85, and $130 at Camcarb. Hydrotech Hydroponics only sells 20 lb tanks, but they can order different sized tanks for you (upon request). However, be aware that they simply call up Camcarb and ask them to deliver the tanks to them, and they will charge you extra on top of Camcarb's CO2 tank pricing.

Regarding refills: Only Dry Ice & Gases are open on Saturday, all the other stores listed above are only open Monday - Friday.
For a 10 pound cylinder, the refill costs are as follows (updated October 23 2012):
Camcarb $20 + tax
Norwood $20 + tax
Herbert Williams: $36.33 + tax
Dry Ice & Gases: $25.80 + tax

Last edited by Darkblade48; 01-12-2014 at 03:10 PM..
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Old 02-03-2010, 09:07 PM   #2
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Default 2) Regulator

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.

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:

Dual stage regulators:

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.

Last edited by Darkblade48; 11-07-2014 at 12:17 PM..
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Old 02-03-2010, 09:13 PM   #3
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Default 3) Needle/Metering Valve

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.

Here is a source (Thanks Mr. Fishies) for a some dealers in Mississauga:

Clippard Dealer
Wainbee Limited
5789 Coopers Avenue
Mississauga, ON L4Z 4S6
(905) 568-1700

Fabco Dealer
Sempress Canada Ltd
3580A Wolfedale Road
Mississauga, Ontario
(905) 949-2324

Effective November 23, 2012

9-3250 Ridgeway Drive
Mississauga, Ontario
L5L 5Y6

Phone: 905.606.2324
Fax: 905.606.2544

Air & Hydraulic Supplies
2200 Markham Road
Toronto, ON
M1B 2W4
(416) 321-8884 ‎

Here is a pricing for the NV55 needle valve (as of 2009)

Fabco Needle Valve
P/N: NV-55
$39.99 (Sempress)

$30.00 + tax (Air & Hydraulic)

*Note 1: The Fabco NV55 contains #10/32 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.

Last edited by Darkblade48; 11-06-2012 at 11:43 PM..
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Old 02-03-2010, 09:17 PM   #4
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Phenomenal write-up, I know many people will get good use out of this. Can anyone say sticky! Again great job.
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Old 02-03-2010, 09:20 PM   #5
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Default Optional (?) Parts

Here now, are the optional parts of a pressurized CO2 setup. While the aforementioned CO2 tank, regulator and needle valve are absolutely essential, the following pieces of equipment, while totally optional, are highly recommended.

These are:

4) Solenoid
5) Bubble Counter
6) Diffuser
7) Drop Checker
8) Miscellaneous equipment (check valve, airline tubing)
9) "Luxury" items (pH controller)

Let us begin with 4) Solenoid

A solenoid is an electronically controlled valve that opens/closes depending on whether electricity is flowing through it or not. For pressurized CO2 purposes, we normally use a "normally closed" solenoid. This means that when there is no electricity, the solenoid is closed, and no CO2 flows. When there is electricity, the solenoid is open, and CO2 flows.

A solenoid provides the option of putting your CO2 onto a timer and/or a pH controller, so that your CO2 will turn on/off automatically. This is beneficial, as it can prolong the amount of time your CO2 will last (i.e. rather than having it on for 24 hours, you can turn it off at night, when plants are no longer photosynthesizing).

Here are some good solenoid brands that I can recommend (in no particular order):
Burkert (Model #: 6011, 6011A or 2822)*
Clippard (Model #: MME-2PDS-D110)*
Fabco (Model #: 3853-04-A287)*

Of these 3, the Clippard is the only one (as far as I know) that has the handy feature of having a red LED that indicates when the solenoid is open, and CO2 is flowing. However, many users have reported that the solenoid does get quite warm (sometimes to the point where you cannot leave your hand on it comfortably). The other three brands do not seem to have this overheating issue, but also do not possess the same LED.

Most solenoids run ~$30

Here is some more information (Thanks Mr. Fishies):

From Sempress Canada (Fabco Dealer):

Fabco Directional Control Valve
P/N: 3853-O4-A287

Prices as of 2012.

*Note: These model numbers are for solenoids with a 1/8" female NPT ports on either side. If you wish to have different port sizes, I can forward you the PDF with the appropriate information.

*Note 2: Here is a data sheet for the Fabco solenoid for those that are interested

Last edited by Darkblade48; 11-03-2012 at 12:15 AM..
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Old 02-03-2010, 09:31 PM   #6
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Default 5) Bubble Counter

The next piece of equipment we will discuss is the Bubble Counter.

A bubble counter allows us to easily determine the flow rate of the CO2 that is going into the aquarium. We often refer to the flow rate as "bubbles per second." The bubble counter is filled with fluid (it can be water, glycerin, or even mineral oil. The latter two are sometimes preferred because bubbles flow through the liquid slower, making it easier to count. In addition, they do not evaporate like water does), and as gas flows through, bubbles are generated so that you can count your bubble rate.

Many different types of bubble counters exist, from in-line ones, to DIY ones, to commercially bought bubble counters. They all perform the same function, at different costs. Some people prefer one over the other due to aesthetics, size constraints, etc., but in the end, they perform the same function.

Not much else to say on this piece of equipment

Last edited by Darkblade48; 02-04-2010 at 02:02 AM..
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Old 02-03-2010, 09:33 PM   #7
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great advice

i hope this is stickied
75 gallon Planted Aquarium

Only a dead fish always swim with the stream - Childe
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Old 02-03-2010, 09:35 PM   #8
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Default 6) Diffuser

An effective method of introducing CO2 into your tank is also required. If CO2 bubbles are reaching the surface of the water in your aquarium, then much of it is being lost and you are not getting CO2 dissolved into your water column. As such, an effective method of getting CO2 to dissolve is required.

From my previous article, I will just copy/paste the various methods of getting CO2 into your water:

1) Bell Diffuser: A passive method of CO2 diffusion, this relies on the assumption that CO2 will dissolve into the water column faster than the CO2 is produced (not likely). Not an effective method of introducing CO2 into the aquarium.
2) Feeding the CO2 tube into a filter intake: Slightly more efficient, this method allows the CO2 bubbles to be fed into the intake of a filter, allowing the bubbles to be chopped up by the filter impeller. Be warned that this method is said to shorten the lifespan of the filter impeller.
3) Commercially available "bubble ladders": Hagen makes a product that is known as "bubble ladder". This product allows CO2 bubbles to travel a long a track, allowing the CO2 more time to dissolve into the water column. The ladder is quite large and bulky (in my opinion), and some people may find it aesthetically unpleasing.
4) Ceramic disc diffuser: Typically a glass diffuser that contains a ceramic disc with miniature pores. These diffusers were first made by ADA (Aqua Design Amano). Such diffusers rely on the small pores on the ceramic disc to adequately create mini-CO2 bubbles, vastly increasing the rate of CO2 dissolution in water.
5) Inline CO2 reactor: Most arguably the best method of CO2 dissolution, the inline CO2 reactor is inline with a (canister) filter output. Using this method, the CO2 is very effectively dissolved.
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Old 02-03-2010, 09:41 PM   #9
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Default 7) Drop Checker

Most likely the newest addition to measuring CO2 levels, a drop checker consists of an airspace between the liquid inside the drop checker and the water in the aquarium. Carbon dioxide readily diffuses outwards from water into the air; as such, the carbon dioxide in the aquarium will readily diffuse into the airspace in the drop checker. The liquid inside the drop checker contains a solution of known kH (i.e. 4 or 5 dkH) with an indicator (bromothymol blue (BTB)) which serves as a good indicator of CO2 dissolution. The CO2 that is in the airspace of the drop checker will readily diffuse into the drop checker solution, changing the colour of the BTB indicator.

Different drop checkers exist today. Red Sea makes one, ADA makes one, Cal Aqua makes several, some can be found on eBay etc. Of course, you can also DIY one yourself. They all work essentially the same, and perform the same function. Some people prefer one brand over the other due to aesthetics and/or ease of comparing the colours.

Here are some instructions for making your own DIY drop checker.

In addition to a drop checker, a reference solution is required when using a drop checker. This is usually a 4 dkH reference solution, but it can also be a 3 or a 5 dkH reference solution. The different dkH reference solutions will turn green (in the presence of BTB) at different CO2 levels (for example, the 4 dkH reference solution turns green at 30 ppm of CO2).

Sometimes, you may find instructions that come with purchased drop checkers to use aquarium water, distilled water, or even tap water. These instructions are incorrect and should be ignored. If you do not use a reference solution, you will get incorrect results when using a drop checker.

Many people (mistakenly) believe that the pH/kH/CO2 relationship is the end-all for measuring CO2 levels. They believe that by measuring the pH and kH of the aquarium water, they will know their CO2 levels. However, this is not the case.

The pH/kH/CO2 relationship can only be used if carbonates are the only buffers in the water. However, in the aquarium, there are other factors that will affect this kH reading (such as phosphate buffers). As a result, the pH/kH/CO2 relationship cannot be used with tank water, tap water, or distilled water.

When making a dkH reference solution, we are only adding carbonates to the water, so only here can we make valid conclusions using the pH/kH/CO2 relationship.

Instructions for making your own 4 dkH reference solution are also in the link above
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Old 02-03-2010, 09:48 PM   #10
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Default 8) Miscellaneous Equipment (Check valve, airline tubing)

Here, we will cover miscellaneous equipment (this maybe considered essential!)

a) Check valve
Placing a check valve is important to prevent a back siphon from occurring. If water were to back siphon, it could go back through the needle valve, destroying your regulator diaphragm. To protect your investment, a check valve provides good protection for a few dollars.

Plastic check valves work fine, but will harden with time (the CO2 makes the plastic brittle), rendering the check valve useless. It is worthwhile to invest a bit more in a brass check valve, as these will not become brittle like their plastic counterparts.

b) Airline tubing
Of course, without airline tubing, you would not be able to get the CO2 from your CO2 tank into your aquarium, so it goes without saying that you will require airline tubing.

The type of tubing does not really matter. I have used your standard vinyl airline tubing as well as your standard silicone airline tubing. Both work fine for our purposes. Some people will point out that silicone tubing is thousands of times more permeable to CO2 than other types of material (there is a website out there with a table showing permeabilization of the various materials). However, given the low pressures at which we work, and the relatively short distances of tubing (say 10-20 feet, at most), the amount of CO2 gas that is loss through silicone tubing is negligible.

While you can purchase CO2 resistant tubing, I find this to be an unnecessary expense.
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