Another ID thread. Am I in trouble???

[Myka]

You will probably need to be more aggressive than muck has suggested to be rid of these pests. They will sit on corals and block the light so the corals starve to death. If you work on lowering nutrients you will often lower the numbers of flatworms. Siphoning at least weekly...you could try one of those gravel vacuums that has a pump and a bag to catch detritus (in this case flatworms) without removing water. Works like a charm. Once you have the population lowered (you have LOTS), then a product called Flat Worm Exit works very well to be rid of the last remaining of the pests. Some Wrasses may eat flatworms (it is individual), and make good prophylactics, but are not usually capable of depleting a population like yours.

Do some Googling...lots of info.