Explain: White drum is my sump,with 12 inches of media / bio balls ,The sump has a Magdrive #9 as my return pump. All the tanks I drilled in the upper left corner .water flows though the bulkheads to a 1 1/2 in PVC drain line that drains though a spray bar over the top of the media.The return lines are one inch pvc that is reduced to the 1/2" at valve. Red handles are the return valves . They refill the tanks from the Magdrive #9. Cycle over flow and refill. I also have 1 " pvc loop for my air . Its valved at the back of each tank.
For water changes , I turn off magdrive #9 . over top of the white barrel /sump are 2 one inch valves one is the return to tanks the 2nd is to pump out to sump pump .Water change is about 35 gallons I do that 3 times a week some times more it so easy. Than I have a hose hooked up to refill the sump. you can see the hose in Pixs # 9 and #10. I use the same hose all over my fishroom. The rest of my tanks I siphon into the 35 gal rubbermaid can that has a Magdrive #12 that I roll over to my sink Pix # 10 and pump out there. The room works pretty good for me. This is the second one I built. The first room has been running for 3 years and the owner does his water changes on 26 tanks in his $2000. custom suit at his lunch time.
I hope I explained it well. Your welcome to come see it in action .