What causes tangles in the line when spinning with a fixed spool reel. All of the reels that my wife and I use seem to develop a tangled knot just down from the shock leader after about 20 or so casts. Is my line to heavy (12-18lbs depending on reel size)? Are they just c**p reels, two of which are Diawa reels with so called 'twist buster'. They have all been loaded in accordance with the instructions.