I am going to be welding some 3/4" steel at work and have been messing around with wire speeds and voltages. When I crank the voltage up to 30+ it seems like slag gets pushed ahead of the puddle. It doesn't happen as much when I crank the wire speed up around 600 ipm with .45 lincoln ultracore wire. The Miller calculator says 390 ipm and 29-30 volts which runs pretty bad, but I'm not using the same gas they specify, I'm using C25. Any suggestions or comments are appreciated.