The light I prefer for indoor growing is the Ceramic
metal halide, called the "Color Master" Bulb by Phillipps. It has good red and blue, it is made to work in a
hps fixture with a Magnetic
ballast. These
bulbs only coe in 250 and 400 watt sizes, and you have to order either horizontal or vertical, as they are not interchangeable.
I have had good luck with it, it's really the best of both
lights.