CUC don't take nutrients out of the water, they are what aquarist call inverts that fulfill certain desirable niches within the closed ecosystem, the most important of these niches for this particular reference (water quality and gorgonian) would be that of the detritivore, such as hermit crabs, some sp. Of polychaete worms, and many others. That while they don't remove nutrients they remove the detritus before it turns into dissolved nutrients. Also filter feeders, my favorite being the porcelain crab will aid in removing food particles from the water column before they settle, thus added addition nutrients.
This will only be one of the components in my nutrient control, I will be running a skimmer, media reactor with sea gel, matrix bio, and a macro algae refugium.
Aquariums are ecosystems we are privileged to own, and should be treated with the full level of care we can supply