or about 2-3000 lumens per square foot. but yeah the cfls' would work just fine at a 24/0 or a 18/6 light get a fan on them too to strengthen stems and minimize stretching. ghet your lights as close as possible, use hand test. plavce hand at plant tops, move light till hand is warm, not hot. This is perfect height for lights, which will have to be adjusted as plants grow. USe the HPS for flowering.