Just using 2 low wattage CFL's, 36W total, about a foot above.
Takes forever for the roots to show, 10 days or more I suppose, but I'm not using a rooting compound.
I'm not methodical about it, so most of the cuttings are above the water, of 12 there might be 2 in the water. The stems being moist is the important part.
I change the water once or twice a week, and recommend useing a water treatment. H2O2, Hydro-Sparkle, PondZyme something like that.
Night.