Re: What do you use? - coals
I use three coconaras, fully burned red on stove--flipped at least twice--on a 32" KM with a vortex bowl.
The coals are positioned in a triangle around the outer edge of the vortex bowl and are not moved during the smoke session.
I find that if the pack and shisha is good, ,then the smoke session can go nearly two hours with full flavor and only a minor drop in smoke density around an hour and a half.
However, when using my egyptian clay bowl I only use two cn's as the bowl is much smaller and three would be way too much heat. This is complicated though, as CN's can't be moved--they break if you try and pick them up--which makes the hole punch design critical for this setup.
I haven't found anything better than CN's, although I really do want to try natural wood eventually . . .