IMO it sounds like a maintenance issue more than a line quality issue to me. If it is at the knot, then you need to tie a better knot. If it is a couple inches above your knot, then your hooks and bill may be beating up that portion and you need to retie more. If it is breaking about 5-6' up from your knot then you could be damaging your line during storage with the tip top of the rod. If it is randomly breaking at the spool then backlashes are causing damage and eventually breaking.