Ask away my friend.. bearing in mind I'm no expert.. here we go..
Yes.. water in the wee fitting and out the big one when it floods to a height.. flood height is adjustable.. the fittings are in sections.. im at max height off one set of fittings, £10, but 2 sets would let u flood higher if required.
And yes.. the nute mix then drains right back into the res underneath, £10 B & M storage box lol, and we go again.. recirculating. Pump in the res on a timer sets length and frequency of floods per day.
My res only holds about 35L so I only changed it out completely once.. to switch to flower nutes, cuz by that stage they were drinking a few litres a day so it needed a top up of fresh nute mix every few days.. now these skoosh are in full flower I'm topping up about 10L of nute mix every 2/3 days.. so.. the res is effectively changing itself over a period of 8/9 days.. and it's working.. res size is very important I think depending on your set up and how long u want to leave shit unattended lol
Phew.. and breathe in.. hope that covered it mucker.. hit me back if ya need anything else