Does raising the salinity in a reef tank kill ich? I know it does in freshwater, but they're different organisms. I would not do a pure freshwater dip, that's seriously stressful and is risky. Dipping won't do any good unless it's no longer present in the water column anyway. If you can, you can place all the fish in a smaller quarantine tank, and treat them in there. Long enough to leave the original tank without a host so that the ich dies off.
125 malawi cichlid, 110 Discus, 75 reef, 30 reef, 27 reef, 4 planted