Ok, your lighting time is good, if your using a light that doesn't put out a lot of heat, then move your plants as close to the top as you can.....when i used floros(40 watts), i had my plants no more than 4"(4 inches) away from the lights, i was also letting them grow into the lights actually touching the bulbs and there will not be any problems.......if your growing under a hot bulb, then place your hand as close as you can up under the lights, then move them away until you can't feel the heat, place the plants so that their tops are far enough away from the heat, then exhaust the heat out the room if possible, the easiest way is to open your grow room door from time to time if you can't afford to by a exhaust system.....