The LAST big upgrade

[lastlight]

What are the angled walls on the overflow for? Just to keep detritus from settling in it? Or am I looking at the drawing wrong?

With all those holes I'm guess you must be using a 3/4" bottom minimum. What did your previous builders suggest? All those bulkheads personally scare me but if I knew they'd never be an issue I'd do a CL as well. Most have dismissed them but I will be using one on the next build. Only difference is I'm taking all my piping over the top of the tank. Never an issue so long is inlet and outlet always remain submerged in an outage.