How are you controlling temps? I am only using T5's now (excited to be moving to a place where I can hoop up my HPS) so during the last few months I've had to run a heater, what I do is put the heater on the timer so that it kicks on when the lights do, I keep my room around 76. At night when it was 30 out side it dipped down to 60, I got worried and put the heater back on full time after a week because the one plant that I had in there that turns purp was close to finish (the rest still had 5-8 weeks when my Dynamite was 3 weeks from done).
When I get a bigger setup I'm going to invest in a more automated system using a thermostat and all. I'm going to be starting some Deep Purple seeds next month, so interested in getting some deep purple coloring.