Call me a fool but I use Lureflash Sinkit. £1.90 from Yorkshire game angling with free delivery. Does the job, removes the shine of the mono and has a consistent texture unlike bankside mud. Because it comes in a handy container I don't have to move much if I change my cast in the middle of the river
Have tried Xink and although it worked it has a really bad habit of re-enacting a certain oil companies gulf of mexico disaster. It also doesn't remove shine from the line.
Only use that on my klink hammers now to rectify an over exuberant application of floatant. Won't replace it when it runs out.