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Yes. But first try cranking the heat. You want to gradually raise temps to 87 degrees and keep it there until a week after the last spot disappears. Meds are a last resort with ich good luck!
If it comes back I honestly wouldn't treat again. First thing I would do is raise the temps.
Carbon removes meds from the water, so my best guess is yes, there are no drugs in your water to treat the fish. If your treatment is unsuccessful, then carbon is the culprit.
Remember, ick shows up on the fish in its feeding stage. When it falls off, your fish may look better, but when ick falls off it goes into its reproduction stage. So in short, that one spot that you don't see on the fish anymore is about to become hundreds of new spores.