Allot of you may allready know this, but I've noticed an influx of new players to the forums so here is some friendly advice for you folks that use c02.

Put your tanks in the freezer and get them nice and cold. When you bring them to where ever you get them filled, keep them in a cooler with some cold packs until you are ready to fill them.

The reason why is because you get a better fill if your co2 tanks are chilled. You get more gas less liquid. I do beieve which in turn gives you a better fill.

From observing others and asking questions.

Why am I wrong? If so sorry, just trying to help.

Yeah I allways empty my tanks before I want them refilled.

Thanks for the aditional input doode.

you want more liquid than gas in it to get more shots. the liquid turns into gas. more gas than liquid, less shots. more liquid, more potential gas.

its like propane, would you rather have a half full tank with more gas than liquid, or a full tank with more liquid which will turn into a gas?

most legitimate paintball fillers can do a complete fill if they are willing to lose a little CO2 in the process.  The filler will usually dump the remaining CO2 that is in the bottle.  Then do a partial fill and dump that out as well.  This how they chill the tanks, since evaporating CO2 chills the bottles.  However, I do my own fills for three reasons.  First, I know I will get a full fill.  Secondly, it is an inconvenience for me do drive an hour one way to get it done by someone else that might not give me a complete fill.  And thirdly, cost.  I can get approximately 60 20oz fills from 75lb bulk tank for $30.  To pay someone to do the filling for me, it would cost about $180 to $240 for that many fills.  And not to mention, it is on hand.  So anytime I need to fill a tank, I can. 

But regarding freezing your tanks first:  I have been freezing my tanks for a few months now and have not had any problems.  I get a full fill out of it without wasting any CO2 than I have to.  Of course, I always drain my tanks before freezing them.  I don't want a chunk of dry ice in their when I dump the remaining out and it is already frozen.

I feel the benefits of doing it myself is worth it.  However, this is not something anyone should think they can just do it.  Things that are required to do fills:  Bulk CO2 source, an approved filling station for CO2, and definitely a scale.  I have seen people not use a scale to fill their tanks and then have seen those tank's burst disks go.  luckily that was the most of it.  There is also alot of reading material on CO2 pressures in relation to temperature and proper ways to do the fills.  I recomend everyone who thinks they can fill a tank understand this and is trained by experienced personel first.

A Rubik's cube has 43,252,003,274,489,856,000 possible combinations.

Kevin Z wrote: When you take them to get filled the tech will empty the remaining CO2 first, chilling the tank. It is not necessary to freeze first, nor empty the leftover CO2 before going. The deal is that the liquid CO2 will hit the warm tank and immediately evaporate, pressurizing the tank and no more transfer can take place. So the tank needs to be cold to minimize evaporation so the tank can be filled with liquid before the pressure gets high enough to equalize.

this guy knows what hes talkin about and the field or shop should chill the tank for you if they dont, dont go there agian unless you have to

Ahem you want liquid in your tanks not in your gun.

if you got less liquid in your tank you will get less shots out of the same tank. its actualy a prity eligant system if you take the time to figure it out.

Chilling is only a factor if your filling your own tanks so you can get more fills out of a 100lb tank. i personaly dont botherhowever having too much liquid in a tank can be a problem too. if you get to much you will tend to such allot into your gun unless you run remote and are standing. if there is a single drop of liquid in your tank its at 800ish psi any way.

as for the acid thing i never knew that i think im gunna hydro my tanks now just to be shure. hay you may have saved a life today... you never know?