very very easy to do....

find a square plastic container.. heavier construction the best and atleast 8" deep...

also you will need a resevoir, preferably with a lid... simple storage bin from the store works...

drill 2 holes (fitting the fittings you will purchase at your local hydro supplier for intake and overflow).. put the fittings in.. connect the hose to the pump you purchase at the same store...

drop the pump in the resevoir, take another hose and connect it to the overflow fitting and put that in the resevoir.. the overflow will be about 2" -3" high (above the bottom of your tray)..

connect the power supply to a timer.. depending on your medium (hydroton/rockwool etc.).. i use hydroton and flood every 2 hours for 15 minutes, you will flood only 3-4 times a day with rockwool....

your up and running now....

its simple and you can build it cheap... just be careful with the fittings.. make sure you drill the correct sizes..

good luck and i hope this helps..

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~cheers