Well how much space do you have? If you have the space and can put up some ventilation put up a high wattage bulb because you will get your money back from it in bud. Here is a rule of thumb a 70 will cover an area of 1x1 a 250 will cover an area of 2x2 a 400 will cover an area of 3x3 a 600 will cover an area of 4x4 a 1000 will cover an area of 5x5 as you go up your plants will look more impressive so if you have the space go with a 600 its the ideal plant light and 2 plants should get you a nice yeild. If you are looking to do a small light in a small space definately scrog.
im looking at a 400 hps. is scrog a hydro system or do i just use soil. i have pretty much an area of 7ft by 7ft by 7ft, h, l, w . so what do u reccomend i do for a 400. and i think a 600 is too expensive so just the 400 and maybe 4 ft 40w floros( four altogether)