I think there are so many different possible arguments but I feel there is one that simplifies it. We strive to achieve a perfect replica of an ocean reef within our small enclosures. We do everything we can to do an elaborate balancing act among many different types of symbiotic organisms. Considering that close to 100% of the rocky stubstrata of any natural reef is covered in coraline I think the benefits outweigh any down side.
Plus, not all of the rock in your tank is covered with coraline. Bottoms, backs, and sides that butt up to other rocks. This still leaves a very porous chunk of rock that's available to micro organisms.
Bottom line, if there's anyone who's concerned about their live rock having too much coraline, I'm happy to trade them for some freshly bleached,porous rock.:yes:
Disclaimer- I don't know much about the whole reef keeping world yet. I'm basing this all on what's logical given what I know about biology and physics.