I'm sorry.... I think I am missing that description.... I'm a visual girl so I really have to scrunch up my nose to try and picture something. Did you mention an overflow wall in that description or just pipes? You need a wall.

Did you mean a 6" diameter pipe? You'll have more noise than niagra falls.

I don't know what your experience level is with building tank stuff but it's best to start simple. An overflow may sound simple but is a very fine tuned piece of equipment, if you will, that can give you all sorts of trouble if not done correctly. Start simplier IMO. I've built many things... but trying to get my 50 gallon pent converted to a reef ready tank almost resulted in it flying out the window.