First of all, the 4100K fluorescent tubes are the wrong kelvin rating to grow weed successfully; you want to shoot for at least a rating of 5500K or above, because these wavelength band carries the most useable light for your plants. As well, fluorescent do not put out nearly enough lumens to successfully vegetate your plants past a couple of inches(unless your are using a lot of bulbs or are growing with t5's), and certainly will not flower your plants very well. My suggestion, either you go with numerous cfls, or you invest in a mh/hps ballast system, you will be thanking yourself in the end.