Ya I may be explaining it slightly wrong or something, the basic principle is the water exiting the "sealed" barrel creates a Vacuum which then sucks more water into the barrel threw the intake, water can not exit the intake because of the 1 way valve so it has to exit the outlet pipe, and since no or little air is entering the system its a constant suction I thought I saw a youtube video of someone doing it but now i'm having trouble finding it. I will have to ask my buddy who originally told me about it and maybe he can give me the link again.

You may even leave some air in the barrel at the start I can't remember.