I have two 70 watt HPS above 4 plants in 2x2-ish space. They are complete assemblies with ballast & reflector that I bought at the Depot. I have 3 big(42w I think) 2700k CFL's for side lighting, two on the outside, and one in the middle of the 4 plants. Veg is great, plants are bushier than my outdoor grow finished last year. About to switch them to 12/12 this weekend