One question about E6. I think I remember reading, but this maybe for C41 color negative only, is that you may get "tar" on stuff like the developer tank?

Is this a really big problem, e.g. needing attention in the sense of regular cleaning, and if so, what do you use to remove it? (what is this tar anyway?)

In addition: I guess this also means using a dedicated color development tank, so no developing of BW in the same tank? Any advice?