Paintball Gun CO2 Tank Basics

High pressure air and CO2 are both used to power paintball markers. CO2 cartridges and tanks are the most common, however, because they are cheaper and it is easier to get them refilled. While high pressure air tanks are more expensive, they can increase your performance. This is why some of the more seasoned players choose high pressure air over CO2; however the cost and availability of CO2 make it the more popular choice. Understanding the properties of CO2 will not only make you a safer player on the paintball field, but will also give you a better idea of how your gun works and just how your power source can affect your game.

Both the liquid and the gas form of CO2 may exist in your tank at any given time; and sometimes both at the same time. It is the gas form that powers your paintball marker, though. If the liquid form enters the valve of your marker you may experience some problems. The liquid CO2 can cause random fluctuations in velocity as well as damage the o-rings inside the marker. The fluctuations in velocity can cause your marker to shoot irregularly and your accuracy will vary.

To prevent liquid CO2 from entering into the valve of your marker, always be sure to hold the gun pointing upward when not in use. Carrying the gun pointing at the ground will shift the liquid CO2 to the front of the tank allowing it to enter the valve and eventually damage your o-rings. Other options you have to protect your marker from liquid CO2 are to install an “anti-siphon” piece that helps allow only air into your gun or upgrade to an expansion chamber. The expansion chamber is an ‘extra little room’ that catches the liquid before it enters the gun and equalizes the temperature of the CO2 before firing.

If liquid CO2 is already in your paintball gun you will know by the white discharge accompanying your paintball when you fire. The easy way to remove the CO2 is to point your marker upward and fire the gun repeatedly until there is no more discharge. Make sure to continue carrying the marker pointed upward to avoid any further leakage.

“Pin Valve Tanks” are the most common types of paintball gun CO2 tanks. The size ranges from 30 grams to 20 ounces and come in a variety of shapes. They are cheap, easy to find, and easy to refill; this is why they are so popular. The large variety allows you to choose the size and shape tank that best suits your paintball marker and your style of play. You can refill your CO2 tank at most any paintball field, commercial air tank supply companies, gun and firearm stores, Bass Pro Shops, and possibly even your local fire department.

You must use a CO2 tank until it is completely empty before refilling it. Topping off your tank is not an option. Also, it is recommended that you allow someone who has some experience with CO2 tanks to do the actual refilling for you. If you are inexperienced with CO2, there is a slight danger and it is possible to injure yourself while refilling it.

The main factor to consider when you are looking to purchase a CO2 tank for your marker is how many shots you expect to get from a tank. The temperature and type of marker you use (as well as many other factors) will play a part in the number of shots you can get from one tank, but here is an estimate of how many shots you should expect to get from various sizes available:

4 oz. – 150-200 shots
9 oz. – 450-500 shots
12 oz. – 500-600 shots
20 oz. – 600-650 shots

It is highly recommended to always purchase your paintball gun CO2 tanks new, especially since they are so cheap to buy. Although a used tank may look like it’s in good condition, there may be faults in the interior of the tank that can’t be seen by the naked eye. If you do choose to go with a used CO2 tank, be sure to “hydrotest” it before use. This will tell you if it is safe to refill or not. It is also a good idea to have any tank you have owned for over a year “hydrotested” as well. This process can be rather expensive, however, and you may be better off just purchasing a new tank.

If you do feel it is a must to continue using an old tank without testing it though, don’t try refilling any tanks with deep scratches or dents. Be careful not to damage the threads as you remove it from the gun or remote line. If the tank begins to unscrew from the brass part (called the valve), stop immediately. If the tank comes off the valve it can become a missile and may cause serious injury, even death.

Proper care of your CO2 cylinder doesn’t take much work and is very important to keep up with. Keep the o-ring from drying out by regularly applying a few drops of oil to it. Also, be sure to replace the o-ring whenever you notice any cracks, fraying or if it dries out. Thread saver caps are very useful in protecting the threads from getting bent or damaged. Store extra tanks in a cool environment and away from any heat source that may cause it to expand and malfunction.

CO2 tanks are cheap to replace, but if you maintain them correctly you can safely go as long as a year before replacing it. Purchase a tank cover to help keep it in prime condition. The power source of your paintball marker is an essential part of your gear. With CO2 tanks being as cheap and easy to come by as they are, there is no reason to take unnecessary risks with your old tank. For great deals on brand new CO2 tanks, check out a great selection at!