Sun Coral problem - UPDATE

[Van down by the river]

Glad to see things are looking up.
Emily B's method works well to induce reluctant Sun Corals.

I've heard of using a vitamin b additive to stimulate feeding response, but I have not tried this myself.

When it is open ensure you feed as many polyps as possible. If you miss some that is okay as they share nutrients throughout the colony as long as the tissue at the base is connected.