Go with table salt first. Dose a tablespoon per 5g and be sure you dissolve it thoroughly and add carefully and slowly to the tank. All you need is grab a cup of tank water, put salt in it and keep stirring until dissolved completely. Keep salt treatment for two weeks and increase the temperature to at least 86 degrees Fahrenheit. If by 10-14 days, ich still lingers, then you can resort to meds. The heat should increase speed rate of lifecycle thus the free-swimming parasites are quickly hit by the salt. Go with salt first. Meds are simply last resorts.