many piranha owners wonder weather to use co2 or hpa. i sure by now u know that hpa is better. for starters it is cleaner and will run threw your marker better. it also has a gauge on the tank and you can fill it one your marker. if u buy n2 at a field it is often cheap as well. on the other hand co2 tanks are cheaper and the tanks are smaller and lighter.
well lets first talk co2. piranhas well work well on co2 compared to other markers. they have lots of room for the co2 to expand and have volumizers, ram air chamber, and expansion chambers. if u want to buy a co2 tank you are going to want to buy a PMI tank. they are found any were, are cheap, and are made of aluminum so they are very light.
remember the PMI tanks are the best. with one of these u are also going to want a siphon. http://www.actionvillage.com/is-bin/...AAAECVbkmO6LC.
this takes only the co2 from the tank that has been transformed into a gas. there is also a little trick that can be performed. with co2 you never know when u r going 2 be out of air because it has no gauge. well what you can do is take an asa or on off with a macro line port on each side.(you can get these any were and most ppl will give them away) what you do is put it one your marker just like the asa you have now but then you put a gauge in the other macro line port. (gauges are often free to.) this will tell you how much psi is in your tank. although it will always be at about 400psi it can atleast give u some idea between enough left and little or no co2.
HPA- first of ill tell you that every HPA tank will perform the same. weather u spend 40 or 400. the only difference is weight, size, and the amount of air the tank can hold. the tanks are slightly different depending on brand but that is the same with anything. with that said you would probably be best of with a 47/3k.they run at about 75 new and 40 used. the crossfire tanks tend to be lighter than the PMI tanks and i would recommend it over a PMI tank but once again it is still preference and either tank is going to be about the same. i would advise you to buy used. tanks either work or they don't work. if it is new or used it will be the same.