Above my 300 gal system. with the 180 gal main tank on the left, it is under a patio roof, and 125 gal sump on the right is in direct morning sun, but not under a roof.
As you can see, although gravity is needed to run the sump, it doesn't need to be directly below the main tank, as most sumps are placed, just somewhat lower.
It also doesn't use compartments.
Beside the aquatic plants that do a lot of the work (the filtration in the sump, on its right end are mangrove trees (above), roots in the water,, but emergent stems and leaves.
In between the two tanks, but with roots in the water are terrestrial dieffenbachia (aka, dumb cane).
There is one dieffenbachia with roots in the main tanks water (above right) and one with roots in the sump.
A few of the fish species below, the sump takes care of filtration for....
A 10" Gobiomorus above...
A 6 " Machaca (Brycon tetra) below
A few 5" Andinoacara coerleopunctatus Rio Mamoni (below)
And a couple 5" to 6" Awaous banana gobies, below
Because the sun is pretty intense from about 8 AM until noon, floating plants and water lilies are needed to buffer the intense rays, and hold temps down.
