Best filtration for DIY nano sump?

[allsite]

I fused together two acrylic hob filters to make a sump across the back of my 12 gallon long tank. It's been a successful project thus far, freeing up space for more trays. It's running 80gph and has 12 compartments.

So far I'm running the following compartments:

Cheato x4 (with tiny mangrove)
Live rock x3 (slowly removing all of it)
Bio rings x1 (will eventually replace need for rock)
GFO/Purigen x1 (love that it's reusable)
Poly x1

I currently have 2 open and will have 5 open when my bio rings are established. Probably 6 open after going down to 3 cheato.

Some of my current thoughts:
Add uv sterilizer
Run a ton of purigen
attempt a calc reactor
possibly run carbon or chem-pure

I'd like to gather creative ideas for optimization. Perhaps you'd set it up completely different or have an idea of something I should add. My goal is to grow corals in addition to filtration.

 

[DanyL]

Interesting idea, love these HOB filter grid thingy.
Where did you get them?

 

[allsite]

Interesting idea, love these HOB filter grid thingy.
Where did you get them?

Picked up the pair for 55 on ebay. Used Weld-on 16 cement and a dremel to bore out the divider. It was designed to hang inside a tank so I had to do some modifications. Messy but easy work.