See these threads as a starting point:
Common Marine Equipment
Marine FAQ
Some corals feed, but many do not. A lot of people run into trouble polluting their tanks while trying to feed corals that really don't need it. In a tank as small as the Fluval chi, I would absolutely recommend against feeding for the pollution reason. Most corals in the trade are primarily photosynthetic, and the non-photosynthetic species that rely on feeding are actually rather challenging to keep alive. Some photosynthetic species like certain large soft polyps and large-polyp stoney corals (LPS) will feed on meaty foods and the feeding can help them grow faster, but light is still far more important. Any sort of more specialized nutrient or fine particulate dosing beyond that is a pretty advanced thing that is not good to try in even a much larger first marine system.
Be aware that a Fluval chi will actually be quite hard as a starting system because of three things:
1. It is totally tiny in the marine world (5gal). It falls into a category many would consider a "pico" tank, which are the hardest systems to maintain longterm. 50gal is considered a much better starting size, since extra volume means more room for error and more stocking possibilities. Even a 20gal (still a nano) is a better starting size than a 5gal.
2. The stock lighting will not support corals. If you want corals, you would need to mod the system to have a more powerful, marine spectrum light.
/www.fishforums.net/index.php?/topic/428985-sambs-5g-fluval-chi-reef/
