My plants are about two weeks old. they are under a 1000 watt metal halide bulb the bulb is about 5 ft above them(there are 13) i have a fan on the temp is about 90 when light is on and 80 when its off. is that too hot? the humidity is always about 45. a few of them are turning bright yellow on the top leaves and slowing turning yellow on the lower leaves. what should i do help please!