A common mistake anglers around the world make is to use the wrong hook. Don't use a treble hook to fish for Carp. More important is the fact that treble hooks are usually very large and will be rejected by wary fish. A size 6 treble hook is twice the diameter of a size 6 single hook. Treble hooks have narrow openings and their shape is such that a good hookset is not always garunteed.
Trebles also have a tendency to snag on weeds, rocks, and submerged logs.
Hook size and pattern are important , dont go any larger than a size six , as anything else will be too heavy for your floating bait, plus the Carp may be able to see and feel it and spit the bait out. Hooks sizes vary between manufactures and styles. One thing is certain large hooks can scare off fish and small hooks can either pull out of not hook at all. Larger fish need and will take larger hooks. Larger hooks also tend to be stronger.