Only been welding for about two years and it has been MIG with 75/25. Self taught which is scary. Decided to get into TIG since I think I could make nicer welds on the small hobby and yard ornaments I make. Just got the Everlast Power i-TIG 201 this week because of the HF start feature and automatic gas control. Beautiful piece of work and I did managed to get it fired up this weekend. Current tank is 75/25 on my MIG welder. Ran 15cf to my TIG and actually got to get it working a bit. Noticed that most of the things are laid a bead on started looking rusty in a matter of minutes. I assume this was oxidation from the CO2. Considering picking up a 125CF bottle of 100% Argon just for the i-TIG since I still have close to a full large tank of the 75/25. Am I right about the oxidation and should I start using straight Argon immediately (buy a new tank) or wait till my current tank gets replaced? Appreciate your help.