This is very true bozo....I've thought about but don't undestand it myself. The way I see it the air pump pulls water in through the intake. Now that there is a void created everything has to fill and the water fills it from the outtake line.....let me try and think of an example.

Think of it as a siphoning thing. If you have a complete circle and you draw something out from one side that something has fill from somehwhere and it does so from the other side due to gravity.

We need X-Crispi or somebody to explain it....they'll understand the theory behind it I think. Or maybe Stinky.....she gets stuff like that.
Weedhound Reviewed by Weedhound on . GH WATERFARM USERS: SIMPLE RECIRCULATING SYSTEM Ok so I was at my hydro store yesterday and the BRAIN pulls out this kit from GH that makes your w/f set recirculating!! Ordinarily this isn't very exciting news EXCEPT...... Get ready.......:jointsmile: It uses an air pump and drip ring set up to move the water through the system. You do NOT NEED A WATER PUMP! Let me repeat that part: YOU DO NOT NEED A WATER PUMP. IT RUNS OFF A BASIC AIR PUMP. Rating: 5