Exactly Stealth......the only electrical is the air pump and it's actually working on suction to draw the water in and up.....exactly the same way it does in each module.

Slothy....It comes in and up the tube and out the top (picture a drip ring at the top.) Water pops out the top and back into your rez...and the outtake line sends it to the very first waterfarm it's hooked up to by gravity from the resevoir itself just as if you were filling the entire system up through the top of the rez.

The Ph....GH always said you could control you ph and nutes from the central resevoir but anyone who uses them knows thats a bunch of bs......you have to check and adjust each pod individually or you're screwed.....BUT if the water is constantly recirculating you REALLY CAN just check and adjust the ph...in the bottom rez only instead of each individual module. You'll also have a more stable ph in general since the water is constantly remixing and circulating.