Heres my sump tank.
Using Evo return pump 4000 ltr/h , very quiet.
Reef octopus external skimmer , modify it to be in sump withoout feed pump.
Using 2 , 100 microns filter sock , 1 for skimmer , 1 for gravity feed.
5kg of Seachem Matrix and some leftover biohomes.
I find that the Matrix help in reducing nitrates quite well
> last time my 2 feet tank , cycled with 1 small cube of market prawn , ended cycling with 75 ppm nitrates
> now 4 feet tank , used 6 full market prawn , ended cycling with only 25 ppm nitrates