Watch the Filtration online guitar lesson by Stephen Bennett from Fingerstyle Finesse
Here are some of the other components of the tune. The Bb section should be learned as and without variation. Pay attention to the rhythm here.
The third part goes into the key of Cm. This tells us something about the tune; Cm makes the 3rd key (or tonal center) for the tune; certainly not a usual blues form, but I love the way it sounds to shift the key around.
Again, I really try to make the melody sing in Filtration Blues. Of course, the bass line has to be solid and the rhythm has to be steady too. And there is a bit of a backbeat again as well.