I still would like to know what that L thing is.
Those holes for the closed loop would work, you would just have to make sure you have holes drilled in the top of your stand accordingly. Check out Frank Arriaga's build thread: http://www.manhattanreefs.com/forum/tank-threads/24983-265-gallon-tank.html He has closed loop return holes in the bottom of his tank.
Its just a drawing that shows up when you start up google sketchup. I just select it and erase it before I began drawing my sketches.
I missed where you said you are going to use an OM. Breaking up the flow between 2 penductors with a snapper may work, but I don't think you will see a tremendous difference you would see if you were to use a pressure rated pump.Ok... so if the snapper is not a good with enductors then what do you think will work? Keep in mind that the OM Super squirt can only handle up to 2400 gph?
btw... thank you for pointing that out. just another thing I had no clue about.