The herbie method is very simple and efficient. I'm not 100% sure on flow rate, but I had this sane type setup on my 300g and ran a 1200gph pump and my valve was almost closed.
I was actually reading your thread last night and found it very helpful. I can't seem to find a step by step guide for building a herbie setup. I'm 90% sure I get it, but a link with pics and a walk through would be awesome. Also everything I've read on it leads me to believe the drain line outletmust be completely submerged in the sump, is this true? If so I need to change my sump design. Assuming this is true I still want to run multiple filter socks. Would the drain be easy to tune if I had the drain line T off twice to drain into 4 filter socks?