Since there is a Zebrasoma veliferum in the tank a significant amount of food provided to is nori. The type used is shown in the below image and the tang gets usually one quarter of a sheet per day. That is torn up into small fragments, soaked in water, then pored into the feeding ring. Depending on time, that will either be in one hit, or over a half an hour. It will tend to also be provided at the same time with the reef aquarium food that I make up myself.

The brand of nori used for feeding the tang.