Have your lights over your refugium set-up so that they go on as soon as your lights on the main tank go off-thus constant lighting is produced to curb the sexual reproduction that usually takes place every 3-6 months(cycle) for most species! If your caulerpa goes sexual, a sudden and potentially dangerous amount of sexual gametes can be released that can harm other life forms not to mention, it can also be responsible for the notorious whole tank "wipe-out"!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
Caulerpa is invasive and grows fast so prunning will need to be achieved. Many species of caulerpa contain antipredatory compounds thus many herbivors will not eat it so mandatory manual prunning will be necessary!
With the use of caulerpa in your refugium, I would strongly recommend that you perform small water changes weekly and use carbon to remove and dilute the noxious discolorants and exudations, as well as improve the overall water quality by replenishing vital minerals and trace elements to your water column!!!
Hope this helps _________ 125gal.w/Mag9.5 return(dual megaflow)>Mag7 pump Aqua Cev180skimmer.Wave2k Hamilton Reefstar(2)250watthqi(mh)pend.a Yellow, Naso Tang Red Lip Blenny Percula Clown Demoiselles Niger Trigger F. Wrasses Ceriantharia Orn.Shrimp and Stars Hermits Queen Conch asst. snails> Stars Zoos shrooms Montipora Brains Gorgonians Favia Turbinaria(large+small polyp) Acropora Xenia Tridacna (CroceaMaximaSquamosa) Leathers <35+75gal.reef tank as well> 
"IF THE PHONE DOESN'T RING...IT'S ME"  jb  | 
