✔ 最佳答案
It's not necessary to start everything over. If ich doesn't have a fish as a host, it will die off itself within a few weeks. The Quick Cure is about as good as you can get for a medication to cure ich (anything that uses both malachite green and formalin). So if this isn't working for your fish, they may have had too heavy of an infection when you bought them. Also, be sure you have the carbon removed from your filter. If you don't the carbon absorbs the medication, so it's about the same as not adding anything to treat.
It may take a little while before you notice any change on your fish. When the ich parasite is attached to them, they are enclosed in a cyst and aren't affected by the treatment. They can only be killed when they drop off into the water. Another common mistake is that when people no longer see the spots on the fish, the stop treating them - but you should allow 3-5 days after you no longer see any spots to do a water change, just to be sure all of the parasites are killed.
You can help speed up the treatment by increasing the water temperature which speeds up the life cycle of the parasite so they drop off faster. Just do this slowly (change no more than a few degrees each hour) and provide good aeration (to compensate for warmer water holding less dissolved oxygen). A temperature of 86o or more is best (and goldfish can handle this temperature if it's changed slowly), but any increase can help.