Please help with White Widow

I started a white widow 3 weeks ago, it was growing nicely but it stopped growing a week ago, the bottom leaves turned brown and drooped so i cut them off, that has helped the top leaves but this plant is not doing good or growing. I have 2 florecences about 4" from top, 1 compact florescent, I am using medium grade potting soil and i just started feeding it 2 times a week with 35/15/12 powder feed and i misted it with insect and mildew spray. I am posting some pictures tommorrow but please help.

I am building a self contained grow box next week, I have a 400 watt hps and metal halide light, thermostat, humidity gage, small oscilating fan, attached is the design of what i will be building