I have seedlings that are 4 days old since seed under a single 2' 24w T5 light. They are all between 1 and 2 inches tall and realized the are probably stretching for the light being as they were about 10" away. I raised them to be about 3" away now. Is this good? The light doesn't seem to put off much heat at all.
People say that you can keep them about 1" away from the lights because those lights hardly produce any light at all. I would say nothing greater than 3" away would work fine because flourescent lights lose penetration very steeply the further you move them away from your plants.