Hyposalinity is your best option so long as your setup does NOT contain any invertebrates or liverock, both of which would certainly suffer ill effects of the hyposalinity. If you have neither in your system this is the way to go. Slowly lower the specific gravity of your setup from 1.024-1.009 over a 48-72 hour period by adding fresh RO/DI or distilled water and maintain at this level for two weeks minimum. If you specific gravity creeps above the prescribed 1.009 it would be advisable to start the two week hyposalinity period over. Once the two weeks is over raise the specific gravity slowly back to 1.024 by adding saltwater made with either RO/DI or distilled water. Take it from someone with Ich experience, the medications available and freshwater dips are not advisable. Also try to determine what the cause of your ICH outbreak. Are you overstocked, poor water quality, etc... You will need a good hydrometer(one without a swing arm), pH, NO2, and NO3 test kits.
