one advantage of 400-watt systems, are the lower-priced lamps, as well ... Google '1000bulbs' for a very good source of bulbs ... they're in TX, and stand behind their stock (a bulb that arrived broken was immediately replaced, even before they received the broken one back) ... nice people to deal with ... I used their cheap $12 HPS bulbs, and noticed absolutely NO difference, from when I was using the $75+ Hortilux bulbs ... they also used to stock a 400-watt 'conversion' bulb, for about $30, that is a metal-halide lamp, that works with a HPS ballast (actually gives off more lumens than their 'regular' MH lamp, go figure) ... great results with all ... :thumbsup: