In this application, running tight spaced cubes with the intention of doing a spike type, mostly single cola grow, 218 cubes are placed into the table. Thats a full table, less 2 for the fill/drain holes. The tray is first flooded to the top of the cubes, with water at PH 4.7 and allowed to stand for 12 hours. This helps keep them from drifting up in PH. They are then flooded with straight tap water to rid of any debris that may have come in the manufacturing or handling of them. Next they are flooded with PH 5.7 water, at this time the cubes should be at PH 6 and ready to accept clones. This is also a great time to check that your table is level.
Each table is a standard 4'x 8' ebb & flow with 2 x 1000wt HPS air cooled lights. Air stones are added to the table and large four inch rockwool cubes are the medium. The cubes are covered with mylar and "X" cuts into the holes that accept the 1" rockwool cubes. This is done to help keep the roots dark, keep the algae growth down and to reflect a light back up to the plants when they are small. I use a very small submersible pump for pumping the water to the table, a couple of shut off valves are also helpful to control the flow and also keep the water in the table for PH adjusting the cubes. A digital timer is used here so that the flood time can be adjusted to the minute.
Above dual picture, shows prepared table with pre-vegged six inch clones inserted and ready to go. Tables are flooded one hour after lights on and again every two hours after that for a total of six feedings during lights on, nothing is used at night. Flood height is adjusted to roughly three fourths of the cube height, and takes just over six minutes to fill, pump runs for eight minutes.