will i need a water pump???

so i am building my own hydroponic system. it is between a nft system and flood and drain system. it is going to be 30" L, 24"W, 12 " tall. a 9 plants system. kind of like the sticky the admin guy postin for the intermediate grower. so my question is, will the water pressure that drains out be enough to push the water back into the resivoir standing 18inches high when the run off hose is standing only 8" high. this might be a dumb stoner question and someone will say bro your an idiot, but i need to know if i need a water pump for the inside of the grow tray. any comments will help.

STAY HIGH

just have the drain tube set as your water line. 8'' is prolly a bit high. you don't need a second pump to pump the water back into the res, use gravity

the only problem is the water level will be incredibly low in the reservoir tank. its a 20 gallon tubberwear so for me to put it at 8" i would need my water level to be at 7" .

comon hydro guys little feedback. i really think the water pressure will be enough to get it back into the res. but i don want to set erything up and be fucked