Wet/Dry setups will likely out gas all your CO2. If you submerge the drain it will help a lot. Quite a few people use refugiums with an opposite photo cycle. If you fertilize via roots, then it helps keep the water clean and starve algae.
Its also a great grow out for fry. They're raised in the exact same conditions as the display. Just make sure its easy to get into if you put fauna in it. It sucks trying to catch a fast small fish in a tight space.
Thank You. I was thinking about keeping Discus in the tank, and in speaking to lot several hobbyist regarding this tank some had suggested a wet/dry sump, or Refigium. The CO2 issue was also one of my concerns.