Those of us that have experience in operating saltwater or reef aquariums have been dealing with compact florescent bulbs for awhile.
But as a PSA for those newer to the hobby I offer this excerpt.
Actually, I apologize, as it turns out it is strictly prohibited to quote or otherwise "mirror" this information but here is the short version.
1) Disconnect all electricity that is supplied to the aquarium.Remove all live specimens into "new water", in the interest of specimen survival said new water should be properly prepared (temperature, de-chlorination, salinity etc.)
2) Contact local authorities for instructions on how to dispose of mercury contaminated water. Or, I suppose, you could just dump it into the creek out back of your house.
3) Keep in mind that any artificial decorations and any sealants used in the tank design, and by extension, the acrylic used to construct an aquarium must be treated as toxic waste.
Aw, the heck with it, if you bust a compact florescent light into your aquarium everything that was living is dead and everything else is hazmat and should be disposed of by the state.
Get a dog.