Paintball Air Tanks
If you plan on being serious with paintball then you can't cut corners when it comes to buying a tank. A good tank will last years, and transfer from gun to gun. You'll need to get the proper size tank for your body, so that when sighting the marker, the tank fits nicely next to your bicept. Keep in mind that if you're playing on a field that provides free air, you don't need to buy the biggest tank possible, since you'll be refilling after each match.
Types of paintball tanks
CO2 tanks
CO2 paintball tanks have been around for years, and while they've worked great for us, they are no longer the ideal way to power your gun. The CO2 in your tank is actually stored in a liquid form, and when you go to shoot your gun, that liquid is transformed into a gas. This transformation from liquid to gas causes the tank to get very cold (you'll often see frost on the tank) - as you may have noticed, when a tank is cold, the pressure drops, and when there is low pressure, the gun doesn't fire well. So the end result is, when you fire often it will get colder, and the preformance of the gun will suffer. This is one of the reasons that CO2 is not as popular today.
Keep in mind that most fields or tournaments that offer all day air are referring to HPA, and not CO2. I'd recommend calling the field ahead of time to verify that they can fill a CO2 tank, or else you'll need to bring several spare tanks. If the field does refill CO2, expect to pay between 3 and 7 dollars per fill.
So, what are the good points with CO2? The main reason people go with CO2 is the cost of the cylinder - you can often buy these for $20 or less at a local paintball store.
High Pressure Air (HPA) and Nitro tanks
HPA has quickly become the preferred way to power paintball guns, and over the years we've seen more and more guns made for HPA (versus traditional CO2). While a high pressure air or nitro tank may be more expensive to buy, they are usually alot cheaper to refill, allowing you to save money in the long run. there are several advantages as well as disadvantages to using a high pressure tank.
Since the air inside a HPA tank is already a gas, it doesn't need to change forms, and is more stable (meaning you shoot at the same rate). In addition, since HPA guns use a regluator to regulate the air into and out of the gun you get an even more consistant firing pattern. HPA is cleaner and easier on the internal parts of your gun, leaving less residue, and not getting nearly as cold. While CO2 operates at around 850 PSI, you can run a HPI gun down around 450, allowing you to get many more shots per barrel out of compressed air.
The 3000 psi, 4500 psi, or 5000 psi stamped on the side of an HPA tank refers to the pressure capacity. The more pressure inside of a paintball tank, the more shots it can deliver. Want to determine the number of shots that your tank will get? A 3000 PSI tanks deliver about 10 shots per cubic inch (68 ci = 680 shots, 47 ci = 470 shots, 88 ci = 880 shots, 114 ci = 1140 shots). 4500 PSI tanks can deliver 15 shots per inch (68 ci = 1020 shots, 88 ci = 1320 shots, 114 ci = 1720 shots).
Types of paintball tanks:
Fiber Wrapped Tanks: A fiber wrapped tank is the most expensive, lightest, and easiest to damage. You'll need to run a cover on this type of tank, since it's so easy to damage
Aluminum Tanks: This is the middle child of paintball tanks. It's heavier, stronger, and cheaper than Fiber, but not as heavy, strong or cheap as steel. Aluminum is great for a more seasoned paintballer who isn't ready to fork out the money for Fiber.
Steel Tanks: Steel tanks are great for entry level players. They are the cheapest and strongest tanks available, however they are also the heaviest. These tanks to well on most fields and really need alot of abuse to get damaged.