HPA tank versus a Co2 tank?

Answer 1

HPA -- High Pressure Air. Compressed nitrogen/air that is used to power a paintball gun. HPA tanks are more expensive than CO2 tanks, but HPA is more consistent and does not damage your marker. HPA is an essential for high end electronic guns.

CO2 -- Compressed Carbon Dioxide that is used to power a paintball gun. CO2 tanks are much, much cheaper than HPA tanks, but are also more hazardous to use on electronic guns. CO2 has a nasty habit of suddenly turning into a liquid, especially when it is cold outside.

When CO2 turns into a liquid it can have negative effects on velocity and accuracy. Also, for this reason, CO2 is dangerous to use on an electric gun because if liquid CO2 gets into the gun's internal parts it can damage the marker's electrical components permanently.

In short--HPA tanks are expensive but more consistent, and necessary for expensive electronic guns. CO2 is cheap but can have unpleasant side effects, so it should only be used on lower end guns.