Plumbing a tank

So, thanks to ManofCichlids I have a new tank.  I want to set it up as well, but am having a hard time deciding how to plumb it.  I have a aversion to overflow boxes, so I'm looking at drilling it.

It's a 36" x 18" x 16" tank, non-drilled but it has a tempered bottom, so I can't drill the bottom.

I would like to install an overflow on the back, mid-right hand side, but am unsure as to what size of holes to drill in the back glass--I know I want at least two drains, one active and one for emergencies.  I only need to flow 300 gph max, as I will have other flow devices as well in the tank. 

My biggest questions are how to pass the drains through the glass--do I use 2 x 90* elbows--one on each side of the bulkhead, do I try and use 45* elbows?  I'm trying to keep intrusion into the tank space down to a minimum as well. 

Any suggestions?

I only have 2-1" drains on my 90 doing over 1200gph.  You would be fine with even 1-1" i would think, but I would do 2 just for the department of redundancy department.  I would put two small overflow boxes in each top corner maybe 3" - 3.5" square, just enough room to get a down-turned street L in there.  It would help maximize floor space.  Run the rest of the durso parts outside the tank by the wall.  I can help you make the boxes if u can get some material.

rdbrown wrote: Check out the laser cut overflow boxes I made for my 180.

I think I would make them go the full height of the tank for cosmetic reasons, but I would also drill my holes as low as I could on the back of the tank.

Edited by rdbrown - October 30 2007 at 9:42pm

Interesting. I would guess that it is somewhat noisy but would also like to hear from someone more knowledgeable with this.

I really like the look of the overflow boxes rdbrown made, but I like the simplicity of the other overflow.

 Hmm....  now I need to decide where on the back I want to drill my holes--and whether together or apart. I also am debating if I should run 2 one inch pipes or two one and a quarter inch pipes.

One benefit I saw to putting in overflow boxes is the ability to glue ledges or small pieces on the outside of them for supports--be it corals, powerheads, liverock brace....