Overflow Desgin - Looking for feedback

[KrazieCanuck]

Hey guys, I'm looking at setting up my own overflow design and was wondering if you had some feedback on this in case I'm not thinking clearly or taking the right approach.  Never actually designed an overflow so any input is greatly appreciated.

The tank will be either a 75 gallon or 90 gallon (still not purchased, but both are 48" in length).  What I was looking at doing was getting a 1.5" hole drilled in each of the back corners for the overflow and then possibly having a 1" hole drilled in the middle for the return.  The return would be split inside to have the return water flowing both to the left and to the right of the tank.

Now, I would also like to have a coast to coast overflow box that I will be designing and building myself out of acrylic.  I'm thinking two overflow boxes (one for each corner) that go over and hide the bulkhead and overflow pipe (Approx. 4" x 6" x 5" in size).  These two boxes in the corners will be connected by a long 2" x 36" x 3" box at the back of the tank to complete the coast to coast overflow.  These measurements aren't exact right now but are estimates to give you an idea of what I'm thinking.  Also, there would be teeth cut in the top of the entire design to allow the "overflow" of water that would be approx 1" deep, and 1/4" apart.

Hopefully this drawing turns out...
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+       +                                      +       +
++++++                                      ++++++


So, what I'm wondering is...
1. Does this make sense?
2. Should the return be just a hang over the top and not drilled? (being strongly considered)
3. Do the hole sizes sound right?
4. Will the design work, any noticeable flaws?


Thanks in advance for your feedback.

[Funkmotor]

2. Should the return be just a hang over the top and not drilled? (being strongly considered)
4. Will the design work, any noticeable flaws?

Drill it, drill it, drill it.  Do not pass Go, do not collect $200.  Drill it.   

On that much overflow area, the thickness of water going over the edge will be small...you don't need teeth.