[pogodzib]

First off, I you want to truly get the ich out of the system, you should remove ALL of the fish out of the DT and leave it fallow for 6 weeks. Leaving just one fish in your DT gives the ich a host so even if the fish doesn't display any signs of ich, the ich parasite will remain present. Once the other fish are put back in there, they may get ich again since their was a host fish present. There is no reef safe medicine for ich. Garlic will help a fish by building up its immune system, but don't put anything else in a reef tank to treat for ich. They either won't kill the fish or will harm your corals or inverts.

Now of the fish dying issue. The first month or two of the fish being in a tank is the time when the fish are the most stressed out and prone to diseases or issues due to water quality problems. Once a fish has been in the system longer, it gets adjusted to the water parameters and recovers from the stress caused from shipping. The main things that I always look for after a new fish has died is 1.) was it weak from shipping 2.) sick or diseased 3.) picked on by other fish 4.) how are the water parameters. These are usually the primary causes for a new fish dying. Since you've had multiple fish die, I'd eliminate issue #1. You've had some larger/more bold types of fish die and usually you won't get fish that will pick on every species of new fish so I'd also eliminate #3. That leave items #2 and 4. You've already said that you have ich and some of your fish that died are very prone to ich so they may have died of ich without you seeing the ich on the fish. Sometimes you need to look at the fish from the correct angle to see how much ich is really on the fish. Another thought is that your fish may not have ich, but velvet or some other disease. Ich is the most common and has larger spots, but velvet can have similar spots, only smaller. The other issue is water quality. Bioballs+Crushed Coral usually = Nitrates. I know that you have been getting 0ppm with your test kits, but have you tried a second set of test with a different brand of test kit to see if they say zero as well?