I would have to say 99.9% of blues sounds come from overdriven tube combo amps. On your pedal, which I am not familiar with, set the gain(overdrive) low and put the volume high. This will give more of an overdriven sound than distorted sound.

For example, on my Tubescreamer I set the level at 12 o'clock, and the drive at 7 or 8 o'clock.