ive been growing for about 1 year now and it seems like this was a problem from the beginning. the heat never gets above 80, actually i think it would be a too cold problem if any, it gets only down to 65-68 at lights out. i cant seem to figure it out, buddy has same strain so i know its not the strain and the same nutes. res temps are 65-67 with lights on, not sure at night. using general hydro nutes. i have a 8" exhaust fan that pulls thru a carbon filter then thru 2 air cooled light and out...... no intake as there is sufficient air intake under doors, walls ect. never go over bout 950ppm. plant seems to slow growth around week 5 of flower. CANT FIGURE IT OUT!!