I just found a Lux meter and was woundering if this could be a good tool for my new garden. the meter will read up to 20,000Lux. My grow area is 24" x 24" and i am going to use a 150 HPS. every thing that i have read from Ed Rosenthal's books is that any where from 1500-3000 lumens per sq ft is what i should have. So 2'x2'=4 sq ft, my light 16,000 lumens divided by 4 = 4000 lumen per sq ft. Is this correct? or am i just stoned. and how could a Lux meter have any use or advantage with my garden?