also your ventelation is superb if your not getting yellowing, but seriously, move that light up and watch them grow. i knew there was something wrong with the age of these plants and their size.. your doing very well though... and dont take away light. add those flouros on the side or something... thats the beauty of light, if you have the space and can get rid of the heat, then you can just add, add, add onto the light. another thing is, although the temp doesn't seem/feel hot when you stick your hand under the bulb, just realize your not stayin under that light.. one thing i like to do, before i knew exactly what to do, is put my face(more sensitive skin) under the light near the plant.. if you feel hot then your plant is too hot. your plant will tell you everything its doing. when the leaves are curling down, the plant is trying to "get away" for that heat. it will not grow up anymore, this is why your plants are so short. its growth is stunted