Sump Design

[Slick Fork]

I was wondering if you guys could critique my first attempt at designing a sump



It is a tank I picked up fairly cheap. It is all scratched up so I don't want to use it as a display, It will sit slightly below and behind my 100gallon display (hidden in a fish room) and I plan on having the overflow hole at the top plumbed to a 20 gallon rubbermaid below the sump (a sump for the sump if you will!!!) strictly as a safety measure in case something overflows.

I plan on filling the skimmer compartment with xenia to help with nutrient absorbtion. The funky looking structure immediately after the skimmer compartment is eggcrate to facilitate a "benthic zone" something I've been reading about with a lot of interest over at Reef Central (the thread is labeled something about duplexes and is in the advanced topics section). Immediately after the benthic zone I want to put a 4-5" deep sand bed to act as a denitrifier, and stretching out on top of both there will be about 4" to grow Chaeto or some other macro algae.

Please let me know where I could improve this, I haven't started construction or bought any of the supplies yet so don't pull any punches!

Cheers