Hi Sheepy
Try using preston innovations hooklenghts whatever size you feel is good enough for the job,last summer I set up a fox bubble float with 8lb line and about 7 foot hooklenghth with a immatation rubber dog biscuit,I got the carp competing for the chum mixers first,then cast the bubble float beyond them and just drew it back so its on th edge of where they are feeding,and make sure you grease the line,dont use any flourocarbon stuff as it sinks ok,you need to grease the hooklenghth to about 3 inches from the hook,I also used a size ten hook,I had fish to 17lb and lots of smaller fish ,but get them going first before you cast to them or you may just spook them,but very gently draw your floater back,there is no rush to do this ,cos if they are competing they will find your hookbait,,and the enterprise floating dog biscuits are brilliant,they have a small spitshot in them,so hook it on the other side and your hook is out of view,,and even if its rubber you can still dunk it in your glug pot,,and believe me it works,,I tried about 4 times to catch this one fish,,but he just veered away,,I glugged the rubber biscuit,and wallop ,he was mine,so dont forget ,just play around with you lenghth of floating line,but I find that preston innovation line just brilliant for this kind of fishing
hope you have some great success this summer demon demon