The proper way to set your clutch is to first find out the breaking strain with a knot in it(whichever knot you use to tie the swivel on is best). You may be surprised just how much more it breaks at compared to the stated breaking strain, anything from 25% to 50% and more in some cases, very few specialist lines break at their given BS, nearly always more.
Once you have established the breaking strain it is a simple job to fill a bucket with correct BS less 5% at which point the clutch should start to slip, this has to be done at home of course. Always set it at the BS of the weakest part of the set up, either main line or hooklink that way you will not have a problem with breakages.