My T5HO & LED are around 23-24" to the shelves. So the height to the plants varies. Some of the tomatoes are 5" below and the small pings in little dishes are about 22 inches below. The top of the plastic terrariums are around 15" below the lights. Some of the CP's touch the top of the terrarium. The Heli terrarium is 20" from the lights to the top. It's a bit lower so it will be a bit cooler.
I could probably lower the LED one but I want the T5HO's to be at least 2' because of the heat.