Don't dose paraguard in DT. It has ingredients that can kill your bacterial population. You don't want your tank being cycled again after medication, do you?
Also malachite green (one of the ingredients in paraguard) is toxic to many invertebrates.
P.S. I don't like this type of catch-all products. If you are sure its ich, get the fish to a QT and use a product that specializes in curing itch.