Compressed air is the most widely used propellant in paintball as it is easily accessible, can be used on all markers, and is typically less expensive than Co2. There is commonly a lot of confusion with Compressed air tanks and if they can be used on certain markers, but typically if your marker has a ASA (Air Source Adapter) or the part that you screw a tank onto, then it can use a compressed air tank. When it comes to different sizes, there are a lot of options ranging from 45ci to ones that are over 100ci! Although picking the right size tank is mostly a personal preference, there are some ways you can narrow down which one is best for you without seeing them in person, keep in mind that how many shots you will get out of all of these is dependent on a wide variety of variables including weather, marker, paint you are using, ect.
45 cubic inch tanks are commonly used for smaller setups where you may not need much air. Usually you would use this on a mechanical or pump setup, where you want to keep it as light as possible, yet still have plenty of air to get you through a few games, or a big game. Another common use for 45ci/4500psi tanks is for younger kids who struggle with larger tanks. Although these are usually one of the smaller tanks, they are longer than peanut tanks.
48ci / 50ci tanks are commonly referred to a “Peanut air tanks” due to the small size of them they are very short. Usually, this size is best for younger kids who may struggle to use a larger tank because of weight or just overall size. Some people prefer this short style that this allows, however a lot of people find it to be not very ergonomic or comfortable. 48ci/4500psi tanks are made by a variety of brands with multiple different styles.
68ci tanks are easily the most common size tank used in paintball. 68/4500 tanks usually fit most people the best, hence their popularity. This size will usually allow for adequate play regardless of if you are playing in a tournament or just recreationally. 68ci/4500psi tanks are universally similar in sizing by all manufacturers, however there may be some variance to them. It is important to note that sizing for the 68/4500 tanks did change somewhat recently, they became shorter and wider than they previously had been. So, if you had been away from the sport, came back and thought a 68 cubic inch wasn’t the same, you are right!
77ci/ 80ci tanks are about the length of the original 68ci tanks, so they are widely used by people who have played for quite a while. 77ci/4500psi tanks are also a favorite for back players due to the additional air that they can walk onto the field with using these or 80ci/4500psi tanks. If you want to ensure that you do not run out of air on the field, especially while playing tournaments, these are a great option for you!
Larger sized tanks are available such as 88ci, 90ci, and 109ci tanks. These larger sizes are less commonly used and are usually more of a “specialty” tank, used for a very specific purpose such as running a setup for a big game where you intend on shooting a ton of paint!