Thuwad, check on the photos in post # 26 and 27. shows the inside perfectly; next post shows same sytem filled with water and running. See if those work for you because that's exactly the photos I would take again

Your problem in understanding, I thiink, is the your lack of your central res....you don't need the float and all that.....with 4 w/fs I'd go with a 30 or 40 gal rubbermaid to hellp with keeping the solution stable as a central rez. Also if you buy the upgrad kit you get everything you need....for a price If you piecemeal it start with buying an exra pumping colum and drip ring.