!All Resevoir&Irrigation Experts Please Help!

hey guys i have some questions on how to control 4- 4x8 trays with 1 large 300 gallon horizontal polytank..the tank has 2" mft drain outlet on the bottom. flood trays are approx 3ft above floor level.. its pretty easy to get the water to the trays but how would i get it to return back to the res properly..because in my mind 300 gallons would probably flood the tubes and trays all the time due to the gravity of that amount of water.. i really need the this large res to work because im going to automated it with tds and ph controllers with dosing pumps.. im asking you guys for help because im a retarded genious who has the tendency to make thing more difficult than it has to be my mind get to scrambling and i take it too far but i know its some its a layed back logical grower out there that can tell in 3 steps on how to get this res running... by the way the 4 trays are in rows of 2 positioned the long way running parallel to each other so i can have a walk way in the middle..hope you guys can help. here is the schematics

simplicity speaking, you flood trays need to be above your resovior (if not, you would then need 2 pumps, 1 for each direction).

To let the tray flood return to the rez, just make the 2" hole, that connects from the rez, at the top of the rez container (not the bottom as your pictured). This way there will only be a little water max left in the tubes and it will mostly return to the rez.