having listened and taken part in marine concerns where coral is concerned ...
macro algae won't help, ... well wait, it will 'help' but when nutrient levels are high enough to upset the coral/zooxanthella algae symbiotic nature, ... one dies off then the other, ... "help" can mean you've prolonged the inevitable. but it's still going to happen
nutrient levels around coral is a much larger issue.
to solve this is then using every effort to ensure any poop is removed ASAP. water flow to prevent any detritus from accumulating anywhere in the tank so it can be removed (finding out you still have areas it's accumulating).
finding that nutrient levels are still higher than desired, algae scrubbers help but that now means you can have more coral types, ... and the most sensitive coral types are still off-bounds because you still can't get the nutrient levels low enough.
and even at this level any kind of algae isn't going to survive because there simply isn't enough nutrients present to keep the algae alive, and you're still above the threshold of the most sensitive coral.
macroalgae doesn't cut it.
DSB, make that a remote DSB so it can be replaced when it's full
Bare Bottom tanks (no substrate)
water flow, ...
GFO reactor (i forget the other name)
... and likely many more things that are done to keep nutrients down, ... in particular phosphates
and they still can't get them low enough for the more sensitive corals.
macroalgae isn't going to cut it
any organic death is releasing nutrients, and at this point (for most coral, forget the more sensitive ones) levels are already low enough algae has a hard time surviving
what is going on in the wild to allow for this to be maintained, ... it's beyond our knowledge, if it was within our knowledge reefs all over the world wouldn't be dying.
sure macro-algae is fine if you have a marine tank i guess, ... but it's not going to cut it if you add coral