another thing you might want to consider is using a 1000w Metal Halide bulb during this stage.. the bulbs are like 30 bucks maybe fifty at the most, you can get them anywhere.. the HPS is only needed in the flowering stage... plus You will get a much better and quicker result because the spectrums of light vary widely with those bulbs.. different strands vary greatly in thier responses.. i.e. my white widows have yellow shade leaves all the way up but my Monsters do not.. they have both been on the same everything all the way through.. The MH bulb will give the plants what they need to make strong stems and broader leaves.. thus better and healthier plants. Try that.