Cutting - am I using the wrong tool?

[bricot]

I was trying to repair trailer and needed to cut off a 5/8" solid rod, bent in a V that holds chains going to a pivot, off of a piece of 3/8 square tube. The rod is laying flat on the surface of the square tube with the weld at 45 degrees. I have the Powerpro 205 and thought I would give the plasma cutter a try. Since I wasn't cutting completely through anything other than the weld, it seemed I got a lot of blowback and slag/arc on the tip.
Should I have turned up the air pressure? Used a torch instead?

Thanks