Many people have trouble getting rid of ick and they often experience outbreaks later because the ick was never fully eradicated to begin with. Ick is actually easy to get rid of. You just have to stick with treatment so every last parasite is killed in its more vulnerable lifestage. It only takes missing one encysted tomont to have an outbreak of 100s infective theronts.
Forget about the treatment you're using which sounds like 'Ick Cure' or something similar. As
duanes
pointed out, treatment for ick lasts a few weeks. This is why many people have so much trouble getting rid of ick ... they don't treat for the full duration.
The easiest treatment is salt + increased temperature. You can use rock salt, canning salt, kosher salt, table salt ... just sodium chloride. Epsom salt is NOT sodium chloride.
Day 1: Add 1 tablespoon salt per 5 gallons of tank water. Gradually increase the temperature to 82ºF.
Day 2: Add another tablespoon of salt per 5 gallons of tank water. Gradually increase the temperature to 84-86ºF. Be sure there is plenty of surface agitation from a filter return and/or a powerful airstone/airpump. At higher temperatures there is less oxygen in the water so good aeration is important.
Day 3: Leave the salt level at 2 tablespoons per 5 gallons and the temperature at 84-86ºF.
Day 4 and beyond: Do nothing.
If temperature has been at 84º, wait at least 10 days after the last whitespot was visible on any of your fish. Then you can gradually reduce the salt level by performing water changes and gradually reduce the temperature to your normal setting.
If temperature has been at 86º, wait at least 7 days after the last whitespot was visible on any of your fish. Then you can gradually reduce the salt level by performing water changes and gradually reduce the temperature to your normal setting.
Be careful not to spread ick to other tanks. It only takes a drop.
Be sure to read the temperature using a thermometer .. not by the dial on the heater.
**This treatment is NOT for scaleless fish or planted tanks.**
Instead, Seachem Paraguard with increased temperature (82º) can be used but it must be dosed daily per the instructions and treatment must be continued for weeks. Wait at least 10 days until the last whitespot was visible on your fish before stopping treatment with Seachem Paraguard.