This is the practice wheras this Hydro system has a seperate reservoir located below a table or tray. A small submersible pump is inserted into the reservoir, on a timer set to intervals, in order to space out watering events over the entire day. When pump is on it fills the table, and when it shuts off the solution drains back to the res. Although I am describing an automated system; This method can actually be done manually if grower so chooses to go and water the plants several; times a day.
(piks coming soon) Just building the board a bit.