The stuff floating around in the water fitting that discription could be a couple things. Do you have a lion fish? When they are irritated, typically from parasites, they will sloth off excess mucus coating in an attempt to rid them selves of the parasite. it will almost look like they shed their skin.
Do you have any toadstool corals? They often do the same thing, sloth off excess mucus. It to will float around the tank when they release it.
If your fish are experiencing a parasite out break, most likly what you are seeing is related to that. As per what type of parasite your fish have (there is no such thing as Ich in salt water) it for the most part doesn't matter. The commonly encountered types of parasites are all susseptable to the commonly used treatments. Lower salinity (hypo saline) , freshwater dips & copper treatments are all commonly used methods that work very well. If you are unable to employ these types of treatments with your aquarium, large U.V. sterilizers and even better an ozone generator / controller would help solve the problem
Hope this helps...
Joel