When I saw Tiger fish, I was thinking ATF (the big toothy African rapids fish), but now realize from your avatar, you may have been suggesting a datnoid type, which would change things drastically.
Sorry if I misinterpreted.
As to wet dry, or some other.
This is a judgement call, I have some wet dry, and also more submerged type media, and see no difference.
My preference is to use filter socks for mechanical, that are rinsed often, water then passes over a column of media (lava rock, rings, whatever...they are all just substrate for bacteria to grow on) then the sump, simply a box that holds the pump, heater (no mystery, just a box that holds water),
I like my sumps to be wet, filled as far as I can go, but won't overflow in a power outage.
I also think the sump should be about access, if its easy to pull pumps, and other stuff out for maintenance, then it will be done.
here's my bio-column, 4ft high 8" diameter, filled with, lava rock and a scrubbie to collect debris.
I rinse the scrubbie at least every other day
The column sits in a 75 gallon sump for heaters, pump, biowheels, filter socks, etc
My point is to show, the simplicity of, and that a sump is whatever you choose it to be.
I also have some sumps that use only only plants for filtration
