[George]

Corals need energy to grow. IMO, the energy comes from either light or food. We don't know the exact percentage between these two. But I guess it is not a fixed ratio even for a particular coral.

I mean, when a coral has more food to eat, it doesn't need that much light. And vice versa.
In the ocean, there are plenty of plankton and such for corals as food. I never dive or snorkel. But by watching numerous videos of reefs at night, I can see that the reefs turn into a plankton soup at night(may be at day too).
Most of our tanks are almost sterilized when comes to coral food. Therefore we might need more light than usual to keep corals.

Anyway, food for thought.

George