How about this?

Ok guys i'm starting to get carried away with the drilling and now I think it's a good idea to drill my cls too. I have a reeflo snapper already to run it. I know the pump is rather small but it will give me a starting point. So here are my plans.

 

the overflows should be 1.5" or 2", with an external t for the vent. cls out should be 1" or 1.5". schedule 80 ( heavy duty ) holes are a different hole size compared to the standard bulkhead fittings, and the schedule 80 is the way to go.

here are the minimum requirements in regards to distance for drilling glass
x = 1.5 t
y = 4 t
t = glass thickness

measurements are taken from the outer most edge of the hole closest to the edge of the glass.

single hole along side: x from edge
single hole near corner: x from first edge, y from second edge
holes next to each other: x from edge, 4t apart
holes next to each other next to edge: x from first edge, 4t apart, y from second edge

heres a site for ya: http://www.diamond-drill-bit-and-too...Drill/MAIN.htm

 

If you have the budget I would use a Ocean Motion valve on your CL to give you some chaotic water movement. Looks like your going to have a real nice tank once your done.

 

Second the oceans motions, you might want to think about using 2x 1.5" bulk heads instead of just 1x2" this reduces the suction and also gives you more leeway if something were to block the drains.

 

how about 2 2"??

 

He might think he has the budget but I bet his wife doesn't think so!

 

I would skip the closed loop all together. I don't see the reasoning behind forcing yourself into maintaining a specific design based on return locations. I run viny returns so I can move them as needed. Not to mention the heat and power consuption of any serious duty pump. Even external PVC would be better than a CLS IMO....don't go freaking out CLS'ers