Because of the fishes involved you can't use the usual copper treatments. Formalin is a successful method, but you really should remove the animals to quarantine to treat. There is a LOT to know about any and all methods. In my experience ten days is not at all sufficient to deal with marine ich.
If you do decide to do hypo, make sure the water you use is matched for pH. Utility of hypo has been argued, there are people on both sides of the fence. I know that LBAOP uses copper for those fishes that can take it, never saw them use Formalin. But I believe that other aquarists at other P.A.'s do use it. I'm drawing a complete blank on authors to search on, Terry Bartelme I think is the name of one fellow who's written a lot. Steven Pro has as well, so try Googling using their names.
Also, you may want to try searching on WetWebMedia.com, the archives there are EXTENSIVE (use their Google bar at the bottom of the page, check the radio button to search wwm only, then when you get your results, and you'll get a LOT, be sure to hit 'cached' for your specific search terms to be highlighted). Search using hyposalinity treatment marine ich, Formalin treatment marine ich, copper treatment marine ich, combinations, and also Cryptocaryon irritans (marine ich) treatment for scaleless fishes.
You will need to learn about the life cycle of the parasite as well as treatment methodologies in order to really effectively treat without killing your fish.