They are both pure Argon. He only welded 1/8" aluminum. The welder was bought for 1 project (aluminum dock framing) and that was it. The two tanks was because refilling was over a 1 hour drive to get. He didn't want to run out mid project.

Thanks for the link J. Will check it out. I found this also:
http://www.gowelding.org/

Now I just need to wire the garage for 240v (downside of the 180. No 120 volt option)

Here is our new Official Welding Thread: http://www.ca.dsm.org/forums/ubbthreads.php?ubb=showflat&Number=447755