So I did some research (I know shocking) And started some lettuce about 3 weeks ago.
Large large white tray is a flood tray. There is a tub of nutrients underneath. 3 times a day a pump comes on and fills the tray up to the overflow. When the pump turns off the tray drains.
The black tray is a different setup called deep water culture. It is full of solution with an air stone in the bottom to keep it oxygenated.
The plants are growing in cubes of rock wool. I cut holes in a piece of foam board that is floating in the liquid with the plants stuck in.
These were were moved into this system today. I was told this is the quickest way to grow lettuce. We will see, its a test run for now.
The small tray is in the big one so it could be under the same lights for now.
Lights are 4 t8 fluorescents in 2 cheep home depot fixtures, 2 warm white and 2 cool white.
I also just planted 8 more seeds today, hopefully I can keep a constant flow of plants.