How do I get rid of this stuff. I tried moving the infected fish to a separate tank and now all my fish have it. Ive lost two already. Ive tried using one of those salt water ick tratments but it oviously isnt working. I have also been using garlic oil in their food with no sucess. So my question is were do I go from here. It looks like im going to loose my last two fish but will the ick also infect my cleaner shrimp and my live rock? Should I replace the water and the sand?(Tank has been set up for about 9 months) How long should I wait before adding new fish?

I'm still new to salt water. I had a fresh water tank for 12 years that never had any problems.
Thanks!