How do i get a co2 tank fill up?

I bought co2 tank and regulators and timers off a dude from craigslist, since than i went to 8 friggin hydroshops and had no luck!! Bcuz i didnt buy thier tank..I feel like i wasted my $$

I read welding shops and that type of industrial machine shop place can refill CO2 for cheap. Check into it locally via your yellow pages.

go to a welding supply. probally cheaper than a hydro shop too.

Try a welding supply place. Some of them sell gasses too.

Welding supply for sure but they may be refusing to fill them because your tank is out of date and needs to be recertified. If that's the case you'll have problems everywhere without spending a bit of money. It's usually a good idea to buy a new tank and find the regulators and equipment used. I believe most certs are good for 5 years or so.

getting a bottle recertified is easy as going to the weld shop to get it refilled, just a few extra bucks.
the place i use just trades bottles, a full bottle for an empty one and $15.

welding shop for sure or maybe a paintball place if you have one close to you. The welding shop can do the recertifying and it's not expensive and I am pretty sure whiteflour is right about the five year shelf life on a certification, but it's been a while since I got my welding degree or did any welding so I can't say I am 100% sure.

Yea I haven't bought one in a while but the certs actually vary depending on the type of metal and pressure it's built for. Some go longer than 5 for sure but at some point they have to be rebuilt, which makes trade in programs better for small volumes. I'd just get cautious of anyone on craigslist getting rid of them for cheap.