This is absolutely watertight cause I use it to mix things in it. The surface is smooth and not overfilled
Yeah, but look at those blobs at the end of your tracks… I don’t want these blobs.
@Rene_Jurack then print only the top infill slower 
like real slow
Probably, I need to do that :-/
@Rene_Jurack jup. Even if you got a direct drive: try playing around with pressure advance if your using slic3r. Didnt do good for me but well
Would a spiral top finish fill smoother? I think Simplify3D will do spiraled surfaces?
@jerryflyguy well. Slic3r does concentric and spiral infills but mostly they end in the middle with a blob or some lines open hence not watertight
Doing pressure advance in the slicer doesn’t make any sense, it doesn’t know what your accel settings are. If you want advance, use a firmware with working pressure advance like Sailfish, RepRapFirmware, or MachineKit.