I advocate feeding coral. I add phytoplankton once a week and I feed my fish Rod's food once or twice a week which also feeds the corals.
I do not have an SPS only tank so keeping pristine water quality is not as important to me. I try to target feed my acans, brain and torch with a turkey baster.
In Julian Sprung's book: Corals-A Quick Reference Guide...ittells you what you want to feed corals. It's a good reference, but that'sexactly all it is..a reference. I amfinding that nothing in this hobby is absolute.
Example from the book:
Euphyllia glaberescens (Torch)
Feeds on sun, phytoplankton,zooplankton, marine snow, fish feces, fish and shrimp, snails...
For chemical feeding I would recommend Iodine from what corals you mentioned.