More Light + Better Temps = More Growth?

I have added more light for two reasons. 1) To supply the plant with more light that isn't penetrating to the bottom via the 400w HPS. 2) To raise the temps up a bit. I have been running around 69-70 degrees inside the tent during the day. I have noticed that since the temps have dropped in the past couple of weeks, so has the growth rate. I have read on here that photosynthesis is best between 76-78 degrees. I am shooting for around 76-80 degrees since the growth rate seems to be best between the two temps. I have added a 6 lamp 2ft T5 light to see what happens from here on. Any thoughts or suggestions on my adding more light this late in the game? Thanks, as always, in advance.:smokin:

Bump^