I am going to do a DIY sump, for a 90 gallon Tanganyikan setup. This is the first time doing a sump period so I wanted to have people who know what they are doing look over the design.
The sump will be built in a standard 29 gallon 30x12x18. I drew up the following designs in Excel, the numbers along the top/sides are inches. I will be ordering a mag 1200 so with the head losses I plan to end up with about 900 gph. Solid lines are acrylic/glass baffles, dotted lines are egg crate.
Side View:

Water comes in through dual inlets, and through a filter sock which I may or may not use all of the time. Water then goes sideways into another chamber and down through a filter media stack (look at the top view if that is confusing). Mechanical media sponge and fine media on top where I can get it easy, bio media toward the bottom. This will be submerged so it will be ceramic rings or similar canister filter bio media I have laying around. Water comes out the bottom of the media stack and up over the baffle into the refugium/deep sand bed. I am hoping to get some denitrification. The baffles buried in the deep sand bed are to limit water movement (oxygenation) deep in the sand. If this doesn't work...I just have a sandy refugium I guess. Finally through a bubble trap, and very the last baffle will have a cutout in the middle and a slot to install some final media, such as a bonded media pad or even a marineland/emperor type filter cartridge.
Top View:

I want to get excellent mechanical filtration and hopefully some denitrification. I have never used a sump at all before so I am looking for any ideas to improve. Thanks!