I have a 400 watt HPS in a closet right now and 4 plants under it.Its a squeezie,The light will cover a 2x2 area and overall 4x4 area.But the 4 are doing great.Just finishing under the HPS. Veg with shop lights,so in a week will start to flower 4more all the way with the HPS.I hope the 4 will do better with the 400watter than fluorescence.More light better bud.
May luck Be with you Peace