beneficial or not

[germ]

My local fish store says mushroom corals are actually good for a reef system something about carbon dioxide....any ideas

 

[jezzeaepi]

My local fish store says mushroom corals are actually good for a reef system something about carbon dioxide....any ideas

That statement doesn't make any sense. Mushroom corals are a coral, and corals are what you generally what you keep in a reef tank. Why would a coral be beneficial or detrimental? There are several corals that are known to "Chemically compete" with other corals through "allelopathy", notably GSP and leathers, but they are only a problem is you plan on keeping a SPS tank. Even then, many people still have leathers and GSP mixed with their SPS without much issue.
As far as the mushrooms effecting your CO2, that makes no sense. The LFS is just blowing smoke....

 

[germ]

thanks It sounded like smoke to me also but wasn't sure thats why I asked...