Its my first attempt with T5's. I have 2 x 24" 6400K , 2232 Lumen. The 6 kids are in jiffy pellets about 1/2" to 1" in height.
How close do I go with the lights ?
Id go 4 inches or so, put the back of your hand under the light to feel how warm it is, thats how you tell, also monitor your plants. But 4-6" sounds about right