my experience with brown jelly is to remove the infected head/heads asap before it starts to spread.
Unfortunately, there is no known cure. Here is some suggested solution:
Excerpts from REEFSHOW.COM...http://reefshow.com/html/modules.php?name=Content&pa=showpage&pid=60#Brown Jelly
Brown Jelly
Brown Jelly is a bacterial infection composed of opportunistic protozoans and other microorganisms digesting coral tissue. Brown Jelly usually begins at the site of an injury. Brown Jelly can be noticed by what look like brown filaments, or brown/brownish, somewhat transparent masses floating over and above a coral, usually enjoining the polyps of the coral into the mass. This infection can progress rapidly. It can spread through out a system or just infect one coral.
Do not mistake a Brown Jelly infection for algae growing "on" the coral when it first starts. If you notice even a small amount of brownish matter hovering close to a coral polyp you should immediately inspect and treat the coral or the polyps will rapidly disintegrate and more than likly infect other corals as the pathogen is sent streaming throughout your system. The location of the infection is not important, it can occur on the sides, ridges, middle or in just about any other area of the coral.
Bubble Coral, Goniopora, Elegance coral, Frogspawn and other Euphyllia corals, Xenia and Anthellia are some of the corals highly susceptible to this pathogen.
Treatment For Brown Jelly
a) GENTLY Siphon as much as the Jelly Mass as Possible
Remove infected coral and treat with an Iodine Solution like Lugols Solution.
c) make sure that your corals have adequate flow. Not laminar, but multi-directional and random
d) Skim, Poly pads, Activated Carbon are recommended
e) 25% water change.
f) check parameters